Proximal element actuator fixation and release mechanisms

ABSTRACT

Fixation system for engaging tissue of a patient including an implantable fixation device having a first arm and a second arm, a first proximal element, a second proximal element, and a coupling member. The system includes a delivery device having a catheter, a shaft extending through the at least one lumen of the catheter, a first proximal element actuator and a second proximal element actuator. The second end portions of the first proximal element actuator and second proximal element actuator can be coupled to at least one of the shaft and the coupling member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority U.S. Provisional Application No.62/874,280, the disclosure of which is incorporated herein by reference.

BACKGROUND 1. Field of the Invention

The present invention relates generally to medical methods, devices, andsystems. In particular, the present invention relates to methods,devices, and systems for the endovascular, percutaneous or minimallyinvasive surgical treatment of bodily tissues, such as tissueapproximation or valve repair. More particularly, the present inventionrelates to repair of valves of the heart and venous valves.

Mitral valve regurgitation is characterized by retrograde flow from theleft ventricle of a heart through an incompetent mitral valve into theleft atrium. During a normal cycle of heart contraction (systole), themitral valve acts as a check valve to prevent flow of oxygenated bloodback into the left atrium. In this way, the oxygenated blood is pumpedinto the aorta through the aortic valve. Regurgitation of the valve cansignificantly decrease the pumping efficiency of the heart, placing thepatient at risk of severe, progressive heart failure.

Mitral valve regurgitation can result from a number of differentmechanical defects in the mitral valve or the left ventricular wall. Thevalve leaflets, the valve chordae which connect the leaflets to thepapillary muscles, the papillary muscles or the left ventricular wallmay be damaged or otherwise dysfunctional. Commonly, the valve annulusmay be damaged, dilated, or weakened limiting the ability of the mitralvalve to close adequately against the high pressures of the leftventricle.

The most common treatments for mitral valve regurgitation rely on valvereplacement or repair including leaflet and annulus remodeling, thelatter generally referred to as valve annuloplasty. A recent techniquefor mitral valve repair which relies on suturing adjacent segments ofthe opposed valve leaflets together is referred to as the “bow-tie” or“edge-to-edge” technique. While all these techniques can be veryeffective, they usually rely on open heart surgery where the patient'schest is opened, typically via a sternotomy, and the patient placed oncardiopulmonary bypass. The need to both open the chest and place thepatient on bypass is traumatic and has associated high mortality andmorbidity. More recently, minimally invasive catheter based procedureshave been developed to deliver implantable clips to the incompetentvalve. These clips are used to fasten a portion of the valve leafletstogether, thereby reducing the regurgitation. While the clips appear tobe promising, delivery and deployment of the clip can be challenging. Insome situations, it may be challenging to visualize the clip and valveleaflets using techniques such as fluoroscopy and echocardiography.Therefore, improved attachment mechanisms and attachment evaluationmethods would be desirable.

For these reasons, it would be desirable to provide improved methods,devices, and systems for performing the repair of mitral and othercardiac valves. Such methods, devices, and systems should preferably notrequire open chest access and be capable of being performed eitherendovascularly, i.e., using devices which are advanced to the heart froma point in the patient's vasculature remote from the heart or by aminimally invasive approach. Further, such devices and systems shouldprovide features which allow easier delivery of fixation devices, aswell as repositioning and optional removal of the fixation device priorto fixation to ensure optimal placement. Still more preferably, themethods, devices, and systems would be useful for repair of tissues inthe body other than heart valves. At least some of these objectives willbe met by the inventions described hereinbelow.

2. Description of the Related Art

Minimally invasive and percutaneous techniques for coapting andmodifying mitral valve leaflets to treat mitral valve regurgitation aredescribed in PCT Publication Nos. WO 98/35638; WO 99/00059; WO 99/01377;and WO 00/03759.

Maisano et al. (1998) Eur. J. Cardiothorac. Surg. 13:240-246; Fucci etal. (1995) Eur. J. Cardiothorac. Surg. 9:621-627; and Umana et al.(1998) Ann. Thorac. Surg. 66:1640-1646, describe open surgicalprocedures for performing “edge-to-edge” or “bow-tie” mitral valverepair where edges of the opposed valve leaflets are sutured together tolessen regurgitation. Dec and Fuster (1994) N. Engl. J. Med.331:1564-1575 and Alvarez et al. (1996) J. Thorac. Cardiovasc. Surg.112:238-247 are review articles discussing the nature of and treatmentsfor dilated cardiomyopathy.

Mitral valve annuloplasty is described in the following publications.Bach and Bolling (1996) Am. J. Cardiol. 78:966-969; Kameda et al. (1996)Ann. Thorac. Surg. 61:1829-1832; Bach and Bolling (1995) Am. Heart J.129:1165-1170; and Bolling et al. (1995) 109:676-683. Linear segmentalannuloplasty for mitral valve repair is described in Ricchi et al.(1997) Ann. Thorac. Surg. 63:1805-1806. Tricuspid valve annuloplasty isdescribed in McCarthy and Cosgrove (1997) Ann. Thorac. Surg. 64:267-268;Tager et al. (1998) Am. J. Cardiol. 81:1013-1016; and Abe et al. (1989)Ann. Thorac. Surg. 48:670-676.

Percutaneous transluminal cardiac repair procedures are described inPark et al. (1978) Circulation 58:600-608; Uchida et al. (1991) Am.Heart J. 121: 1221-1224; and Ali Khan et al. (1991) Cathet. Cardiovasc.Diagn. 23:257-262.

Endovascular cardiac valve replacement is described in U.S. Pat. Nos.5,840,081; 5,411,552; 5,554,185; 5,332,402; 4,994,077; and 4,056,854.See also U.S. Pat. No. 3,671,979 which describes a catheter fortemporary placement of an artificial heart valve.

Other percutaneous and endovascular cardiac repair procedures aredescribed in U.S. Pat. Nos. 4,917,089; 4,484,579; and 3,874,338; and PCTPublication No. WO 91/01689.

Thoracoscopic and other minimally invasive heart valve repair andreplacement procedures are described in U.S. Pat. Nos. 5,855,614;5,829,447; 5,823,956; 5,797,960; 5,769,812; and 5,718,725.

BRIEF SUMMARY

In accordance with the disclosed subject matter, a fixation system forengaging tissue of a patient is provided. The system includes animplantable fixation device having a first arm and a second arm, a firstproximal element moveable relative to the first arm between a firstposition and a second position, a second proximal element moveablerelative to the second arm between a first position and a secondposition, and a coupling member. The system also includes a deliverydevice having a catheter with a proximal end portion and a distal endportion, the catheter defining at least one lumen extending between theproximal end portion and the distal end portion, and a shaft extendingthrough the at least one lumen and releasably coupled to the couplingmember. The delivery device further includes a first proximal elementactuator extending through the at least one lumen, the first proximalelement actuator having a first end portion, a second end portion, andan intermediate portion between the first end portion and the second endportion, wherein the first proximal element actuator is coupled to thefirst proximal element at the intermediate portion of the first proximalelement actuator and actuatable to move the first proximal elementbetween the first position and the second position, and a secondproximal element actuator extending through the at least one lumen, thesecond proximal element actuator having a first end portion, a secondend portion, and an intermediate portion between the first end portionand the second end portion, wherein the second proximal element actuatoris coupled to the second proximal element at the intermediate portion ofthe second proximal element actuator and actuatable to move the secondproximal element between the first position and the second position. Thesecond end portion of the first proximal element actuator and secondproximal element actuator, respectively, can be coupled to at least oneof the shaft and the coupling member.

In accordance with the disclosed subject matter, the first and secondproximal element actuators can be coupled to the shaft and/or couplingmember in a variety of ways to enhance performance. For example, thefirst proximal element actuator and the second proximal element actuatorcan be released from the at least one of the shaft and the couplingmember by decoupling the shaft and coupling member. The second endportion of the first proximal element actuator can include a first loopand the second end portion of the second proximal element actuator caninclude a second loop. Each of the first and second loops can bedisposed around at least one of the shaft and the coupling member whenthe shaft and the coupling member are coupled together.

The second end portion of the first proximal element actuator caninclude a first catch element and the second end portion of the secondproximal element actuator can include a second catch element. The firstcatch element can be a first ball and the second catch element can be asecond ball. Alternatively, the first catch element can be a firsttrumpet and the second catch element can be a second trumpet. The firstcatch element can be configured to be received within a first opening inthe shaft, and the second catch element can be configured to be receivedwithin a second opening in the shaft. The first catch element and secondcatch element can be held in the corresponding first opening and secondopening by an actuator rod received within a lumen of the shaft. Thefirst catch element and the second catch element can be received betweenthe shaft and the coupling member, when releasably coupled together.

The delivery system can further include a first proximal elementactuator mandrel and a second proximal element actuator mandrel, thefirst and second proximal element actuator mandrels extending throughthe at least one lumen of the catheter. The first proximal elementactuator mandrel can be configured to releasably anchor the firstproximal element actuator between the first proximal element actuatormandrel and the catheter, and the second proximal element actuatormandrel can be configured to releasably anchor the second proximalelement actuator between the second proximal element actuator mandreland the catheter. The delivery device can further include a first cutterconfigured to cut the first proximal element actuator to thereby releasethe first proximal element. The delivery device can include a secondcutter configured to cut the second proximal element actuator to therebyrelease the second proximal element.

In accordance with another aspect of the disclosed subject matter, afixation system for engaging tissue of a patient is provided. The systemincludes an implantable fixation device having a first arm and a secondarm, a first proximal element moveable relative to the first arm betweena first position and a second position, a second proximal elementmoveable relative to the second arm between a first position and asecond position, and a coupling member. The system also includes adelivery device having a catheter having a proximal end portion and adistal end portion, the catheter defining at least one lumen extendingbetween the proximal end portion and the distal end portion and a shaftextending through the at least one lumen and releasably coupled to thecoupling member. The delivery device includes a first proximal elementactuator extending through the at least one lumen, the first proximalelement actuator having a first end portion and a second end portion,wherein the first proximal element actuator is coupled to the firstproximal element at the second end portion of the first proximal elementactuator and actuatable to move the first proximal element between thefirst position and the second position, and a second proximal elementactuator extending through the at least one lumen, the second proximalelement actuator having a first end portion and a second end portion,wherein the second proximal element actuator is coupled to the secondproximal element at the second end portion of the second proximalelement actuator and actuatable to move the second proximal elementbetween the first position and the second position.

The first proximal element actuator and the second proximal elementactuator can each include an outer sheath having a first window, aninner mandrel axially moveable relative the outer sheath, and a sutureextending from the outer sheath and defining a loop. The suture can beactuatable between a captured position wherein the suture extends intothe window of the outer sheath and receives the inner mandrel throughthe loop, and a released position.

The first proximal element actuator and the second proximal elementactuator can each include an outer sheath axially moveable relative aninner member having a distal pincer, wherein the outer sheath isconfigured to close the pincer by moving distally relative the innermember and to open the pincer by moving proximally relative the innermember. The first proximal element actuator and the second proximalelement actuator can each include a weakened region proximal the secondend portion of the first proximal element actuator.

In accordance with the disclosed subject matter, a fixation system forengaging tissue of a patient including an implantable fixation deviceand a delivery device is provided. The implantable fixation device caninclude a first arm and a second arm, a first proximal element moveablerelative to the first arm between a first position and a secondposition, a second proximal element moveable relative to the second armbetween a first position and a second position, and a coupling member.The delivery device can include a catheter having a proximal end portionand a distal end portion, the catheter defining at least one lumenextending between the proximal end portion and the distal end portionand a shaft extending through the at least one lumen and releasablycoupled to the coupling member. The delivery device can also include afirst proximal element actuator extending distally through the at leastone lumen and back proximally through the at least one lumen to define aloop extending from the distal end portion of the catheter, the loop ofthe first proximal element actuator can be coupled to the first proximalelement and actuatable to move the first proximal element between thefirst position and second position, and a second proximal elementactuator extending distally through the at least one lumen and backproximally through the at least one lumen to define a loop extendingfrom the distal end portion of the catheter, the loop of the secondproximal element actuator can be coupled to the second proximal elementand actuatable to move the second proximal element between the firstposition and second position. The loop defined by the first proximalelement actuator and the loop defined by the second proximal elementactuator can be each coupled to at least one of the shaft and thecoupling member.

Other aspects of the nature and advantages of the disclosed subjectmatter are set forth in the detailed description set forth below, takenin conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the left ventricle and left atrium of the heartduring systole.

FIG. 2A illustrates free edges of leaflets in normal coaptation, andFIG. 2B illustrates the free edges in regurgitative coaptation.

FIGS. 3A-3C illustrate grasping of the leaflets with a fixation device,inversion of the distal elements of the fixation device and removal ofthe fixation device, respectively.

FIG. 4 illustrates the position of the fixation device in a desiredorientation relative to the leaflets.

FIGS. 5A-5B and 6A-6B illustrate exemplary embodiments of couplingmechanisms of the instant application.

FIGS. 7A-7B and 8A-8B illustrate the movement of fixation elements of anembodiment of the fixation device of the present invention.

FIG. 9 illustrates another embodiment of the fixation device.

FIGS. 10A-10B, 11A-11B, 12A-12B, 13A-13B and 14-16 illustrate thefixation device of FIG. 7 in various possible positions duringintroduction and placement of the device within the body to perform atherapeutic procedure.

FIGS. 17A-17C illustrate the fixation device in various positions.

FIGS. 18-19 illustrate an embodiment of the fixation device includingproximal elements and a locking mechanism.

FIGS. 20-21 provide a cross-sectional view of the locking mechanism inthe unlocked and locked positions respectively.

FIGS. 22A, 22B, and 23-27 illustrate another embodiment of fixationdevice having a covering and independent actuation.

FIG. 28 illustrates another embodiment of a fixation device including agripper pusher.

FIG. 29 illustrates an embodiment of a fixation device havingindependent proximal element actuation.

FIG. 30 illustrates another embodiment of a fixation device havingindependent proximal element actuation.

FIG. 31 illustrates another embodiment of a fixation device havingindependent proximal element actuation.

FIG. 32 illustrates another embodiment of a fixation device havingindependent proximal element actuation.

FIG. 33 illustrates another embodiment of a fixation device havingindependent proximal element actuation.

FIGS. 34-35 illustrates another embodiment of a fixation device havingindependent proximal element actuation with a single actuator.

FIGS. 36-40 illustrate the fixation device of FIG. 9 with a gripperpusher.

FIGS. 41-46 illustrate another embodiment of a fixation device of with agripper pusher and independent actuation.

FIG. 47 illustrates another embodiment of a fixation device having agripper pusher and independent actuation.

FIG. 48 illustrates another embodiment of a fixation device having agripper pusher and independent actuation with a single actuator.

FIGS. 49A-49C, 50A-50E, 51A-51B and 52A-52G illustrate variousembodiments of coupling a proximal element line to a proximal element ofa fixation device.

FIGS. 53, 54A-D, 55A-C and 56A-B illustrate an actuator rod and relatedcomponents according to another embodiment of the fixation device.

FIGS. 57 and 58 illustrate an embodiment for releasably coupling agripper pusher to a fixation device.

FIGS. 59A and 59B illustrate the configuration of a proximal elementactuator.

FIGS. 60A and 60B illustrate another configuration of a proximal elementactuator.

FIG. 61 schematically illustrates a heart with functional mitralregurgitation.

FIGS. 62A-B schematically illustrate sequential leaflet capture in aheart with functional mitral regurgitation using an implantable fixationdevice of the disclosed subject matter.

FIGS. 63A-B schematically illustrate a heart with degenerative mitralregurgitation.

FIGS. 64A-B schematically illustrate sequential leaflet capture in aheart with degenerative mitral regurgitation using an implantablefixation device of the disclosed subject matter.

FIGS. 65A-B illustrate an enlarged view of a distal end portion of adelivery system shaft having holes to receive a catch element inaccordance with the disclosed subject matter.

FIG. 65C is a cross-section view of the distal end portion of a deliverysystem shaft of FIG. 65B.

FIG. 65D illustrates a distal end portion of a proximal element actuatorhaving a trumpet catch.

FIG. 65E illustrates an enlarged view of a distal end portion of adelivery shaft having holes to receive a catch element in accordancewith the disclosed subject matter.

FIG. 65F illustrates a distal end portion of a proximal element actuatorhaving a ball catch.

FIG. 65G illustrates an enlarged view of a distal end portion of adelivery shaft having holes to receive a catch element in accordancewith the disclosed subject matter.

FIG. 65H illustrates an enlarged view of the edge of the hole of thedelivery shaft having a fillet edge in accordance with the disclosedsubject matter.

FIG. 65I illustrates an enlarged view of the edge of the hole of thedelivery shaft having a chamfer with rounded edges in accordance withthe disclosed subject matter.

FIG. 65J illustrates an enlarged view of the delivery shaft including anangle-reduction feature in accordance with the disclosed subject matter.

FIGS. 66A-D illustrate an enlarged view of a distal end portion of adelivery system shaft, a proximal element actuator, and a proximalelement, and coupling therebetween using a loop in accordance with thedisclosed subject matter.

FIG. 67 illustrates an enlarged view of a distal end portion of adelivery system shaft, a proximal element actuator, and a proximalelement, and coupling therebetween using a mandrel in accordance withthe disclosed subject matter.

FIG. 68 illustrates an enlarged view of a distal end portion of adelivery system shaft, a proximal element actuator, and a proximalelement, and coupling therebetween using a cutter in accordance with thedisclosed subject matter.

FIGS. 69A-B illustrate an enlarged view of a distal end portion of aproximal element actuator and a proximal element, and couplingtherebetween using a loop in accordance with the disclosed subjectmatter.

FIG. 70 illustrates an enlarged view of a distal end portion of aproximal element actuator and a proximal element, and couplingtherebetween using a pincer in accordance with the disclosed subjectmatter.

FIG. 71 illustrates an enlarged view of a distal end portion of aproximal element actuator and a proximal element, and couplingtherebetween using a neck-down region in accordance with the disclosedsubject matter.

DETAILED DESCRIPTION OF THE INVENTION 1. Cardiac Physiology

The left ventricle LV of a normal heart H in systole is illustrated inFIG. 1. The left ventricle LV is contracting and blood flows outwardlythrough the tricuspid (aortic) valve AV in the direction of the arrows.Back flow of blood or “regurgitation” through the mitral valve MV isprevented since the mitral valve is configured as a “check valve” whichprevents back flow when pressure in the left ventricle is higher thanthat in the left atrium LA. The mitral valve MV comprises a pair ofleaflets having free edges FE which meet evenly to close, as illustratedin FIG. 1. The opposite ends of the leaflets LF are attached to thesurrounding heart structure along an annular region referred to as theannulus AN. The free edges FE of the leaflets LF are secured to thelower portions of the left ventricle LV through chordae tendineae CT(referred to hereinafter as the chordae) which include a plurality ofbranching tendons secured over the lower surfaces of each of the valveleaflets LF. The chordae CT in turn, are attached to the papillarymuscles PM which extend upwardly from the lower portions of the leftventricle and intraventricular septum IVS.

A number of structural defects in the heart can cause mitral valveregurgitation. Regurgitation occurs when the valve leaflets do not closeproperly allowing leakage from the ventricle into the atrium. As shownin FIG. 2A, the free edges of the anterior and posterior leafletsnormally meet along a line of coaptation C. An example of a defectcausing regurgitation is shown in FIG. 2B. Here an enlargement of theheart causes the mitral annulus to become enlarged, making it impossiblefor the free edges FE to meet during systole. This results in a gap Gwhich allows blood to leak through the valve during ventricular systole.Ruptured or elongated chordae can also cause a valve leaflet to prolapsesince inadequate tension is transmitted to the leaflet via the chordae.While the other leaflet maintains a normal profile, the two valveleaflets do not properly meet and leakage from the left ventricle intothe left atrium will occur. Such regurgitation can also occur inpatients who have suffered ischemic heart disease where the leftventricle does not contract sufficiently to effect proper closure.

2. General Overview

Aspects of the present invention provides methods and devices forgrasping, approximating and fixating tissues such as valve leaflets totreat cardiac valve regurgitation, particularly mitral valveregurgitation. The present invention also provides features that allowrepositioning and removal of the device if so desired, particularly inareas where removal may be hindered by anatomical features such aschordae CT. Such removal would allow the surgeon to reapproach the valvein a new manner if so desired.

Grasping will preferably be atraumatic providing a number of benefits.By atraumatic, it is meant that the devices and methods of the inventionmay be applied to the valve leaflets and then removed without causingany significant clinical impairment of leaflet structure or function.The leaflets and valve continue to function substantially the same asbefore the invention was applied. Thus, some minor penetration ordenting of the leaflets may occur using the invention while stillmeeting the definition of “atraumatic”. This enables the devices of theinvention to be applied to a diseased valve and, if desired, removed orrepositioned without having negatively affected valve function. Inaddition, it will be understood that in some cases it may be necessaryor desirable to pierce or otherwise permanently affect the leafletsduring either grasping, fixing or both. In some of these cases, graspingand fixation may be accomplished by a single device. Although a numberof embodiments are provided to achieve these results, a general overviewof the basic features will be presented herein. Such features are notintended to limit the scope of the invention and are presented with theaim of providing a basis for descriptions of individual embodimentspresented later in the application.

The devices and methods of the invention rely upon the use of aninterventional tool that is positioned near a desired treatment site andused to grasp the target tissue. In endovascular applications, theinterventional tool is typically an interventional catheter. In surgicalapplications, the interventional tool is typically an interventionalinstrument. In preferred embodiments, fixation of the grasped tissue isaccomplished by maintaining grasping with a portion of theinterventional tool which is left behind as an implant. While theinvention may have a variety of applications for tissue approximationand fixation throughout the body, it is particularly well adapted forthe repair of valves, especially cardiac valves such as the mitralvalve. Referring to FIG. 3A, an interventional tool 10, having adelivery device, such as a shaft 12, and a fixation device 14, isillustrated having approached the mitral valve MV from the atrial sideand grasped the leaflets LF. The mitral valve may be accessed eithersurgically or by using endovascular techniques, and either by aretrograde approach through the ventricle or by an antegrade approachthrough the atrium, as described above. For illustration purposes, anantegrade approach is described.

The fixation device 14 is releasably attached to the shaft 12 of theinterventional tool 10 at its distal end. When describing the devices ofthe invention herein, “proximal” shall mean the direction toward the endof the device to be manipulated by the user outside the patient's body,and “distal” shall mean the direction toward the working end of thedevice that is positioned at the treatment site and away from the user.With respect to the mitral valve, proximal shall refer to the atrial orupstream side of the valve leaflets and distal shall refer to theventricular or downstream side of the valve leaflets.

The fixation device 14 generally comprises proximal elements 16 (orgripping elements; wherein “proximal elements” and “gripping elements”are used interchangeably herein) and distal elements 18 (or fixationelements; wherein “distal elements” and “fixation elements” are usedinterchangeably herein) which protrude radially outward and arepositionable on opposite sides of the leaflets LF as shown so as tocapture or retain the leaflets therebetween. The proximal elements 16are preferably comprised of cobalt chromium, nitinol or stainless steel,and the distal elements 18 are preferably comprised of cobalt chromiumor stainless steel, however any suitable materials may be used. Thefixation device 14 is couplable to the shaft 12 by a coupling mechanism17. The coupling mechanism 17 allows the fixation device 14 to detachand be left behind as an implant to hold the leaflets together in thecoapted position.

In some situations, it may be desired to reposition or remove thefixation device 14 after the proximal elements 16, distal elements 18,or both have been deployed to capture the leaflets LF. Suchrepositioning or removal may be desired for a variety of reasons, suchas to reapproach the valve in an attempt to achieve better valvefunction, more optimal positioning of the device 14 on the leaflets,better purchase on the leaflets, to detangle the device 14 fromsurrounding tissue such as chordae, to exchange the device 14 with onehaving a different design, or to abort the fixation procedure, to name afew. To facilitate repositioning or removal of the fixation device 14the distal elements 18 are releasable and optionally invertible to aconfiguration suitable for withdrawal of the device 14 from the valvewithout tangling or interfering with or damaging the chordae, leafletsor other tissue. FIG. 3B illustrates inversion wherein the distalelements 18 are moveable in the direction of arrows 40 to an invertedposition. Likewise, the proximal elements 16 may be raised, if desired.In the inverted position, the device 14 may be repositioned to a desiredorientation wherein the distal elements may then be reverted to agrasping position against the leaflets as in FIG. 3A. Alternatively, thefixation device 14 may be withdrawn (indicated by arrow 42) from theleaflets as shown in FIG. 3C. Such inversion reduces trauma to theleaflets and minimizes any entanglement of the device with surroundingtissues. Once the device 14 has been withdrawn through the valveleaflets, the proximal and distal elements may be moved to a closedposition or configuration suitable for removal from the body or forreinsertion through the mitral valve.

FIG. 4 illustrates the position of the fixation device 14 in a desiredorientation in relation to the leaflets LF. This is a short-axis view ofthe mitral valve MV from the atrial side, therefore, the proximalelements 16 are shown in solid line and the distal elements 18 are shownin dashed line. The proximal and distal elements 16, 18 are positionedto be substantially perpendicular to the line of coaptation C. Thedevice 14 may be moved roughly along the line of coaptation to thelocation of regurgitation. The leaflets LF are held in place so thatduring diastole, as shown in FIG. 4, the leaflets LF remain in positionbetween the elements 16, 18 surrounded by openings O which result fromthe diastolic pressure gradient. Advantageously, leaflets LF are coaptedsuch that their proximal or upstream surfaces are facing each other in avertical orientation, parallel to the direction of blood flow throughmitral valve MV. The upstream surfaces may be brought together so as tobe in contact with one another or may be held slightly apart, but willpreferably be maintained in the vertical orientation in which theupstream surfaces face each other at the point of coaptation. Thissimulates the double orifice geometry of a standard surgical bow-tierepair. Color Doppler echo will show if the regurgitation of the valvehas been reduced. If the resulting mitral flow pattern is satisfactory,the leaflets may be fixed together in this orientation. If the resultingcolor Doppler image shows insufficient improvement in mitralregurgitation, the interventional tool 10 may be repositioned. This maybe repeated until an optimal result is produced wherein the leaflets LFare held in place.

Once the leaflets are coapted in the desired arrangement, the fixationdevice 14 is then detached from the shaft 12 and left behind as animplant to hold the leaflets together in the coapted position. Asmentioned previously, the fixation device 14 is coupled to the shaft 12by a coupling mechanism 17. FIGS. 5A-5B, 6A-6B illustrate exemplaryembodiments of such coupling mechanisms. FIG. 5A shows an upper shaft 20and a detachable lower shaft 22 which are interlocked at a joining lineor mating surface 24. The mating surface 24 may have any shape orcurvature which will allow or facilitate interlocking and laterdetachment. A snuggly fitting outer sheath 26 is positioned over theshafts 20, 22 to cover the mating surface 24 as shown. FIG. 5Billustrates detachment of the lower shaft 22 from the upper shaft 20.This is achieved by retracting the outer sheath 26, so that the matingsurface 24 is exposed, which allows the shafts 20, 22 to separate.

Similarly, FIG. 6A illustrates a tubular upper shaft 28 and a detachabletubular lower shaft 30 which are interlocked at a mating surface 32.Again, the mating surface 32 may have any shape or curvature which willallow or facilitate interlocking and later detachment. The tubular uppershaft 28 and tubular lower shaft 30 form an outer member having an axialchannel. A snuggly fitting rod 34 or inner member is inserted throughthe tubular shafts 28, 30 to bridge the mating surface 32 as shown. FIG.6B illustrates detachment of the lower shaft 30 from the upper shaft 28.This is achieved by retracting the rod 34 to a position above the matingsurface 32 which in turn allows the shafts 28, 30 to separate. Otherexamples of coupling mechanisms are described and illustrated incopending U.S. patent application Ser. No. 09/894,493), incorporatedherein by reference for all purposes.

Similarly, FIG. 6A illustrates a tubular upper shaft 28 and a detachabletubular lower shaft 30 which are interlocked at a mating surface 32.Again, the mating surface 32 may have any shape or curvature which willallow or facilitate interlocking and later detachment. The tubular uppershaft 28 and tubular lower shaft 30 form an outer member having an axialchannel. A snuggly fitting rod 34 or inner member is inserted throughthe tubular shafts 28, 30 to bridge the mating surface 32 as shown. FIG.6B illustrates detachment of the lower shaft 30 from the upper shaft 28.This is achieved by retracting the rod 34 to a position above the matingsurface 32 which in turn allows the shafts 28, 30 to separate. Otherexamples of coupling mechanisms are described and illustrated incopending U.S. patent application Ser. No. 09/894,493, incorporatedherein by reference for all purposes.

3. Fixation Device

A. Introduction and Placement

The fixation device 14 is delivered to the valve or the desired tissueswith the use of a delivery device. The delivery device may be rigid orflexible depending on the application. For endovascular applications,the delivery device comprises a flexible delivery catheter which will bedescribed in later sections. Typically, however, such a cathetercomprises a shaft, having a proximal end and a distal end, and afixation device releasably attached to its distal end. The shaft isusually elongate and flexible, suitable for intravascular introduction.Alternatively, the delivery device may comprise a shorter and lessflexible interventional instrument which may be used for trans-thoracicsurgical introduction through the wall of the heart, although someflexibility and a minimal profile will generally be desirable. Afixation device is releasably couplable with the delivery device asillustrated in FIG. 3A. The fixation device may have a variety of forms,a few embodiments of which will be described herein.

FIGS. 7A-8B illustrate an embodiment of a fixation device 14 in variouspositions or configurations. FIG. 7A illustrates the fixation device 14in a closed configuration for delivery through the patient's vasculatureand, in this example, through the mitral valve. The fixation device 14includes a coupling member 19 which allows detachment of the fixationdevice 14 for implantation. In this example, the coupling member 19 isshown to include the lower shaft 22 and mating surface 24 of FIGS.5A-5B, and therefore the coupling member 19 would function similarly asdescribed above. The fixation device 14 also includes a pair of opposeddistal elements 18, each distal element 18 having an engagement surface50 facing inwardly toward the opposed distal element 18 in the closedconfiguration. Distal elements 18 preferably comprise elongate arms 53,each arm having a proximal end 52 rotatably connected to the couplingmember 19 and a free end 54. Suitable connections for arms 53 tocoupling member 19 include pins, living hinges, or other knownrotational connection mechanisms. In the closed configuration of FIG.7A, free ends 54 point in a first direction such that the arms 53 andengagement surfaces 50 are nearly parallel to each other and to an axis21, and preferably are angled slightly inwardly toward each other. In apreferred embodiment, when tissue is not present between arms 53, thearms 53 may be closed until free ends 54 either touch each other orengage shaft 12 when fixation device 14 is attached thereto, therebyminimizing the profile of the fixation device 14 for passage through adelivery device.

FIGS. 7B-8A illustrate the fixation device 14 in an open positionwherein the engagement surfaces 50 are disposed at a separation angle 56apart, wherein the separation angle 56 is typically up to approximately180 degrees, preferably up to 90-180 degrees, and arms 53 are disposedgenerally symmetrically relative to axis 21. The arms 53 may be moveableto the open position by a variety of actuation mechanisms. For example,a plunger or actuator rod may be advanced through the coupling member19, as indicated by arrow 62, so as to engage a spring or spring loadedactuation mechanism 58 which is attached to the distal elements 18. Byexerting a force against the actuation mechanism 58, the distal elements18 are rotated relative to coupling member 19. The distal elements 18may be held in this open position by the actuator rod against theresistance provided by the spring of the actuation mechanism 58 whichbiases the distal elements 18 toward the closed position of FIG. 7A whenthe distal elements 18 are less than 180 degrees apart. The springloading of the actuation mechanism 58 resists outward movement of theactuation mechanism 58 and urges the device 14 towards the closedposition.

In this embodiment, proximal elements 16 comprise resilient loop-shapedwire forms biased outwardly and attached to the coupling member 19 so asto be biased to an open position shown in FIG. 8A but moveablerotationally inwardly when arms 53 are closed. The wire forms may beflexible enough to be rigidly attached to coupling member 19 andresiliently deflectable inwardly, or they may be attached by arotational coupling such as a pin or living hinge. In use, leaflets LFare positioned between the proximal elements 16 and distal elements 18.Once, the leaflets LF are positioned between the proximal and distalelements 16, 18, the distal elements 18 may be closed, compressing theleaflets between engagement surfaces 50 and proximal elements 18.Depending upon the thickness of the leaflets, the arrangements of theleaflets, the position of the fixation device on the leaflets and otherfactors, the arms 53 may be maintained in the open position of FIG. 7B,moved to the fully closed position of FIG. 7A, or placed in any ofvarious positions in between so as to coapt the leaflets LF and holdthem in the desired position with the desired degree of force. In anycase, the fixation device 14 will remain in place as an implantfollowing detachment from the delivery catheter.

In some situations, as previously mentioned, it may be desirable toreopen the fixation device 14 following initial placement. To reopen thedevice 14, the actuator rod may be readvanced or reinserted through thecoupling member 19 and readvanced to press against the actuationmechanism 58, as previously indicated by arrow 62 in FIG. 7B. Again,such advancement applies a force against the actuation mechanism 58 inthe manner described above thus moving arms 53 outwardly to releaseforce against leaflets and move engagement surfaces 50 away fromproximal elements 16. The leaflets are then free to move relative tofixation device 14. The fixation device 14 may then be repositioned asdesired and the actuator rod retracted to reclose the distal elements 18to coapt the leaflets.

Under some circumstances, it may be further desirable to withdraw thefixation device 14 back through the valve or completely from the patientfollowing initial insertion through the valve. Should this be attemptedwith the clip in the closed or open positions illustrated in FIGS.7A-8A, there may be a risk that arms 53 could interfere or becomeentangled with the chordae, leaflets or other tissues. To avoid this,the fixation element 14 is preferably adapted for inversion of arms 53so that free ends 54 point in a second direction, opposite to the firstdirection in which the free ends 54 pointed in the closed position, eacharm 53 forming an obtuse angle relative to axis 21 as illustrated inFIG. 8B. The arms 53 may be rotated so that the engagement surfaces 50are disposed at a separation angle 56 of up to 360 degrees, andpreferably at least up to 270 degrees. This may be accomplished byexerting a force against actuation mechanism 58 with a push rod orplunger extending through coupling member 19 as described above. In thisembodiment, once the distal elements 18 have rotated beyond 180 degreesapart, the spring loading of the actuation mechanism 58 biases thedistal elements 18 toward the inverted position. The spring loading ofthe actuation mechanism 58 resists outward movement of the actuationmechanism 58 and urges the device 14 towards the inverted position.

With arms 53 in the inverted position, engagement surfaces 50 provide anatraumatic surface deflect tissues as the fixation device is withdrawn.This allows the device to be retracted back through the valve annuluswithout risk of injury to valvular and other tissues. In some cases,once the fixation device 14 has been pulled back through the valve, itwill be desirable to return the device to the closed position forwithdrawal of the device from the body (either through the vasculatureor through a surgical opening).

The embodiment illustrated in FIGS. 7A-8B is assembled from separatecomponents composed of biocompatible materials. The components may beformed from the same or different materials, including but not limitedto stainless steel or other metals, Elgiloy®, nitinol, titanium,tantalum, metal alloys or polymers. Additionally, some or all of thesecomponents may be made of bioabsorbable materials that will be absorbedby surrounding tissues or will dissolve into the bloodstream followingimplantation. It has been found that in mitral valve repair applicationsthe fixation devices of the invention are completely surrounded bytissue within a few months of implantation, after which the devicescould dissolve or be absorbed without negative impact to the repair.

FIG. 9 illustrates another embodiment of a fixation device 14. Here, thefixation device 14 is shown coupled to a shaft 12 to form aninterventional tool 10. The fixation device 14 includes a couplingmember 19 and a pair of opposed distal elements 18. The distal elements18 comprise elongate arms 53, each arm having a proximal end 52rotatably connected to the coupling member 19 and a free end 54. Thefree ends 54 have a rounded shape to minimize interference with andtrauma to surrounding tissue structures. Preferably, each free end 54defines a curvature about two axes, one being an axis 66 perpendicularto longitudinal axis of arms 53. Thus, the engagement surfaces 50 have acupped or concave shape to surface area in contact with tissue and toassist in grasping and holding the valve leaflets. This further allowsarms 53 to nest around the shaft 12 in the closed position to minimizethe profile of the device. Preferably, arms 53 are at least partiallycupped or curved inwardly about their longitudinal axes 66. Also,preferably, each free end 54 defines a curvature about an axis 67perpendicular to axis 66 or the longitudinal axis of arms 53. Thiscurvature is a reverse curvature along the most distal portion of thefree end 54. Likewise, the longitudinal edges of the free ends 54 mayflare outwardly. Both the reverse curvature and flaring minimize traumato the tissue engaged therewith.

In an embodiment suitable for mitral valve repair, the transverse widthacross engagement surfaces 50 (which determines the width of tissueengaged) is at least about 2 mm, usually 3-10 mm, and preferably about4-6 mm. In some situations, a wider engagement is desired wherein theengagement surfaces 50 are larger, for example about 2 cm, or multiplefixation devices are used adjacent to each other. Arms 53 and engagementsurfaces 50 are configured to engage a length of tissue of about 4-10mm, and preferably about 6-8 mm along the longitudinal axis of arms 53.Arms 53 further include a plurality of openings to enhance grip and topromote tissue ingrowth following implantation.

The valve leaflets are grasped between the distal elements 18 andproximal elements 16. In some embodiments, the proximal elements 16 areflexible, resilient, and cantilevered from coupling member 19. Theproximal elements are preferably resiliently biased toward the distalelements. Each proximal element 16 is shaped and positioned to be atleast partially recessed within the concavity of the distal element 18when no tissue is present. When the fixation device 14 is in the openposition, the proximal elements 16 are shaped such that each proximalelement 16 is separated from the engagement surface 50 near the proximalend 52 of arm 53 and slopes toward the engagement surface 50 near thefree end 54 with the free end of the proximal element contactingengagement surface 50, as illustrated in FIG. 9. This shape of theproximal elements 16 accommodates valve leaflets or other tissues ofvarying thicknesses.

Proximal elements 16 include a plurality of openings 63 and scallopedside edges 61 to increase grip on tissue. The proximal elements 16optionally include frictional accessories, frictional features orgrip-enhancing elements to assist in grasping and/or holding theleaflets. In preferred embodiments, the frictional accessories comprisebarbs 60 having tapering pointed tips extending toward engagementsurfaces 50. It may be appreciated that any suitable frictionalaccessories may be used, such as prongs, windings, bands, barbs,grooves, channels, bumps, surface roughening, sintering, high-frictionpads, coverings, coatings or a combination of these. Optionally, magnetsmay be present in the proximal and/or distal elements. It may beappreciated that the mating surfaces will be made from or will includematerial of opposite magnetic charge to cause attraction by magneticforce. For example, the proximal elements and distal elements may eachinclude magnetic material of opposite charge so that tissue is heldunder constant compression between the proximal and distal elements tofacilitate faster healing and ingrowth of tissue. Also, the magneticforce may be used to draw the proximal elements 16 toward the distalelements 18, in addition to or alternatively to biasing of the proximalelements toward the distal elements. This may assist in deployment ofthe proximal elements 16. In another example, the distal elements 18each include magnetic material of opposite charge so that tissuepositioned between the distal elements 18 is held therebetween bymagnetic force.

The proximal elements 16 may be covered with a fabric or other flexiblematerial as described below to enhance grip and tissue ingrowthfollowing implantation. Preferably, when fabrics or coverings are usedin combination with barbs or other frictional features, such featureswill protrude through such fabric or other covering so as to contact anytissue engaged by proximal elements 16.

In an exemplary embodiment, proximal elements 16 are formed frommetallic sheet of a spring-like material using a stamping operationwhich creates openings 63, scalloped edges 61 and barbs 60.Alternatively, proximal elements 16 could be comprised of a spring-likematerial or molded from a biocompatible polymer. It should be noted thatwhile some types of frictional accessories that can be used in thepresent invention may permanently alter or cause some trauma to thetissue engaged thereby, in a preferred embodiment, the frictionalaccessories will be atraumatic and will not injure or otherwise affectthe tissue in a clinically significant way. For example, in the case ofbarbs 60, it has been demonstrated that following engagement of mitralvalve leaflets by fixation device 14, should the device later be removedduring the procedure barbs 60 leave no significant permanent scarring orother impairment of the leaflet tissue and are thus consideredatraumatic.

The fixation device 14 also includes an actuation mechanism 58. In thisembodiment, the actuation mechanism 58 comprises two link members orlegs 68, each leg 68 having a first end 70 which is rotatably joinedwith one of the distal elements 18 at a riveted joint 76 and a secondend 72 which is rotatably joined with a stud 74. The legs 68 arepreferably comprised of a rigid or semi-rigid metal or polymer such asElgiloy®, cobalt chromium or stainless steel, however any suitablematerial may be used. While in the embodiment illustrated both legs 68are pinned to stud 74 by a single rivet 78, it may be appreciated,however, that each leg 68 may be individually attached to the stud 74 bya separate rivet or pin. The stud 74 is joinable with an actuator rod 64(not shown) which extends through the shaft 12 and is axially extendableand retractable to move the stud 74 and therefore the legs 68 whichrotate the distal elements 18 between closed, open and invertedpositions. Likewise, immobilization of the stud 74 holds the legs 68 inplace and therefore holds the distal elements 18 in a desired position.The stud 74 may also be locked in place by a locking feature which willbe further described in later sections.

In any of the embodiments of fixation device 14 disclosed herein, it maybe desirable to provide some mobility or flexibility in distal elements18 and/or proximal elements 16 in the closed position to enable theseelements to move or flex with the opening or closing of the valveleaflets. This provides shock absorption and thereby reduces force onthe leaflets and minimizes the possibility for tearing or other traumato the leaflets. Such mobility or flexibility may be provided by using aflexible, resilient metal or polymer of appropriate thickness toconstruct the distal elements 18. Also, the locking mechanism of thefixation device (described below) may be constructed of flexiblematerials to allow some slight movement of the proximal and distalelements even when locked. Further, the distal elements 18 can beconnected to the coupling mechanism 19 or to actuation mechanism 58 by amechanism that biases the distal element into the closed position(inwardly) but permits the arms to open slightly in response to forcesexerted by the leaflets. For example, rather than being pinned at asingle point, these components may be pinned through a slot that alloweda small amount of translation of the pin in response to forces againstthe arms. A spring is used to bias the pinned component toward one endof the slot.

FIGS. 10A-10B, 11A-11B, 12A-12B, 13A-13B, and FIGS. 14-16 illustrateembodiments of the fixation device 14 of FIG. 9 in various possiblepositions during introduction and placement of the device 14 within thebody to perform a therapeutic procedure. FIG. 10A illustrates anembodiment of an interventional tool 10 delivered through a catheter 86.It may be appreciated that the interventional tool 10 may take the formof a catheter, and likewise, the catheter 86 may take the form of aguide catheter or sheath. However, in this example the termsinterventional tool 10 and catheter 86 will be used. The interventionaltool 10 comprises a fixation device 14 coupled to a shaft 12 and thefixation device 14 is shown in the closed position. FIG. 10B illustratesa similar embodiment of the fixation device of FIG. 10A in a largerview. In the closed position, the opposed pair of distal elements 18 arepositioned so that the engagement surfaces 50 face each other. Eachdistal element 18 comprises an elongate arm 53 having a cupped orconcave shape so that together the arms 53 surround the shaft 12 andoptionally contact each other on opposite sides of the shaft. Thisprovides a low profile for the fixation device 14 which is readilypassable through the catheter 86 and through any anatomical structures,such as the mitral valve. In addition, FIG. 10B further includes anactuation mechanism 58. In this embodiment, the actuation mechanism 58comprises two legs 68 which are each movably coupled to a base 69. Thebase 69 is joined with an actuator rod 64 which extends through theshaft 12 and is used to manipulate the fixation device 14. In someembodiments, the actuator rod 64 attaches directly to the actuationmechanism 58, particularly the base 69. However, the actuator rod 64 mayalternatively attach to a stud 74 which in turn is attached to the base69. In some embodiments, the stud 74 is threaded so that the actuatorrod 64 attaches to the stud 74 by a screw-type action. However, the rod64 and stud 74 may be joined by any mechanism which is releasable toallow the fixation device 14 to be detached from shaft 12.

FIGS. 11A-11B illustrate the fixation device 14 in the open position. Inthe open position, the distal elements 18 are rotated so that theengagement surfaces 50 face a first direction. Distal advancement of thestud 74 relative to coupling member 19 by action of the actuator rod 64applies force to the distal elements 18 which begin to rotate aroundjoints 76 due to freedom of movement in this direction. Such rotationand movement of the distal elements 18 radially outward causes rotationof the legs 68 about joints 80 so that the legs 68 are directly slightlyoutwards. The stud 74 may be advanced to any desired distancecorrelating to a desired separation of the distal elements 18. In theopen position, engagement surfaces 50 are disposed at an acute anglerelative to shaft 12, and are preferably at an angle of between 90 and180 degrees relative to each other. In one embodiment, in the openposition the free ends 54 of arms 53 have a span therebetween of about10-20 mm, usually about 12-18 mm, and preferably about 14-16 mm.

Proximal elements 16 are typically biased outwardly toward arms 53. Theproximal elements 16 may be moved inwardly toward the shaft 12 and heldagainst the shaft 12 with the aid of proximal element lines 90 which canbe in the form of sutures, wires, nitinol wire, rods, cables, polymericlines, or other suitable structures. The proximal element lines 90 maybe connected with the proximal elements 16 by threading the lines 90 ina variety of ways. When the proximal elements 16 have a loop shape, asshown in FIG. 11A, the line 90 may pass through the loop and doubleback. When the proximal elements 16 have an elongate solid shape, asshown in FIG. 11B, the line 90 may pass through one or more of theopenings 63 in the element 16. Further, a line loop 48 may be present ona proximal element 16, also illustrated in FIG. 11B, through which aproximal element line 90 may pass and double back. Such a line loop 48may be useful to reduce friction on proximal element line 90 or when theproximal elements 16 are solid or devoid of other loops or openingsthrough which the proximal element lines 90 may attach. A proximalelement line 90 may attach to the proximal elements 16 by detachablemeans which would allow a single line 90 to be attached to a proximalelement 16 without doubling back and would allow the single line 90 tobe detached directly from the proximal element 16 when desired. Examplesof such detachable means include hooks, snares, clips or breakablecouplings, to name a few. By applying sufficient tension to the proximalelement line 90, the detachable means may be detached from the proximalelement 16 such as by breakage of the coupling. Other mechanisms fordetachment may also be used. Similarly, a lock line 92 may be attachedand detached from a locking mechanism by similar detachable means.

In the open position, the fixation device 14 can engage the tissue whichis to be approximated or treated. The embodiment illustrated in FIGS.9-11 is adapted for repair of the mitral valve using an antegradeapproach from the left atrium. The interventional tool 10 is advancedthrough the mitral valve from the left atrium to the left ventricle. Thedistal elements 18 are oriented to be perpendicular to the line ofcoaptation and then positioned so that the engagement surfaces 50contact the ventricular surface of the valve leaflets, thereby graspingthe leaflets. The proximal elements 16 remain on the atrial side of thevalve leaflets so that the leaflets lie between the proximal and distalelements. In this embodiment, the proximal elements 16 have frictionalaccessories, such as barbs 60 which are directed toward the distalelements 18. However, neither the proximal elements 16 nor the barbs 60contact the leaflets at this time.

The interventional tool 10 may be repeatedly manipulated to repositionthe fixation device 14 so that the leaflets are properly contacted orgrasped at a desired location. Repositioning is achieved with thefixation device in the open position. In some instances, regurgitationmay also be checked while the device 14 is in the open position. Ifregurgitation is not satisfactorily reduced, the device may berepositioned and regurgitation checked again until the desired resultsare achieved.

It may also be desired to invert the fixation device 14 to aid inrepositioning or removal of the fixation device 14. FIGS. 12A-12Billustrate the fixation device 14 in the inverted position. By furtheradvancement of stud 74 relative to coupling member 19, the distalelements 18 are further rotated so that the engagement surfaces 50 faceoutwardly and free ends 54 point distally, with each arm 53 forming anobtuse angle relative to shaft 12. The angle between arms 53 ispreferably in the range of about 270 to 360 degrees. Further advancementof the stud 74 further rotates the distal elements 18 around joints 76.This rotation and movement of the distal elements 18 radially outwardcauses rotation of the legs 68 about joints 80 so that the legs 68 arereturned toward their initial position, generally parallel to eachother. The stud 74 may be advanced to any desired distance correlatingto a desired inversion of the distal elements 18. Preferably, in thefully inverted position, the span between free ends 54 is no more thanabout 20 mm, usually less than about 16 mm, and preferably about 12-14mm. In this illustration, the proximal elements 16 remain positionedagainst the shaft 12 by exerting tension on the proximal element lines90. Thus, a relatively large space may be created between the elements16, 18 for repositioning. In addition, the inverted position allowswithdrawal of the fixation device 14 through the valve while minimizingtrauma to the leaflets. Engagement surfaces 50 provide an atraumaticsurface for deflecting tissue as the fixation device is retractedproximally. It should be further noted that barbs 60 are angled slightlyin the distal direction (away from the free ends of the proximalelements 16), reducing the risk that the barbs will catch on or laceratetissue as the fixation device is withdrawn.

Once the fixation device 14 has been positioned in a desired locationagainst the valve leaflets, the leaflets may then be captured betweenthe proximal elements 16 and the distal elements 18. FIGS. 13A-13Billustrate the fixation device 14 in such a position. Here, the proximalelements 16 are lowered toward the engagement surfaces 50 so that theleaflets are held therebetween. In FIG. 13B, the proximal elements 16are shown to include barbs 60 which may be used to provide atraumaticgripping of the leaflets. Alternatively, larger, more sharply pointedbarbs or other penetration structures may be used to pierce the leafletsto more actively assist in holding them in place. This position issimilar to the open position of FIGS. 11A-11B, however the proximalelements 16 are now lowered toward arms 53 by releasing tension onproximal element lines 90 to compress the leaflet tissue therebetween.At any time, the proximal elements 16 may be raised and the distalelements 18 adjusted or inverted to reposition the fixation device 14,if regurgitation is not sufficiently reduced.

After the leaflets have been captured between the proximal and distalelements 16, 18 in a desired arrangement, the distal elements 18 may belocked to hold the leaflets in this position or the fixation device 14may be returned to or toward a closed position. Such locking will bedescribed in a later section. FIG. 14 illustrates the fixation device 14in the closed position wherein the leaflets (not shown) are captured andcoapted. This is achieved by retraction of the stud 74 proximallyrelative to coupling member 19 so that the legs 68 of the actuationmechanism 58 apply an upwards force to the distal elements 18 which inturn rotate the distal elements 18 so that the engagement surfaces 50again face one another. The released proximal elements 16 which arebiased outwardly toward distal elements 18 are concurrently urgedinwardly by the distal elements 18. The fixation device 14 may then belocked to hold the leaflets in this closed position as described below.

As shown in FIG. 15, the fixation device 14 may then be released fromthe shaft 12. As mentioned, the fixation device 14 is releasablycouplable to the shaft 12 by coupling member 19. FIG. 15 illustrates thecoupling structure, a portion of the shaft 12 to which the couplingmember 19 of the fixation device 14 attaches. As shown, the proximalelement lines 90 may remain attached to the proximal elements 16following detachment from shaft 12 to function as a tether to keep thefixation device 14 connected with the catheter 86. Optionally, aseparate tether coupled between shaft 12 and fixation device 14 may beused expressly for this purpose while the proximal element lines 90 areremoved. In any case, the repair of the leaflets or tissue may beobserved by non-invasive visualization techniques, such asechocardiography, to ensure the desired outcome. If the repair is notdesired, the fixation device 14 may be retrieved with the use of thetether or proximal element lines 90 so as to reconnect coupling member19 with shaft 12.

In an exemplary embodiment, as shown in FIG. 18, proximal element lines90 are elongated flexible threads, wire, cable, sutures or linesextending through shaft 12, looped through proximal elements 16, andextending back through shaft 12 to its proximal end. When detachment isdesired, one end of each line may be released at the proximal end of theshaft 12 and the other end pulled to draw the free end of the linedistally through shaft 12 and through proximal element 16 therebyreleasing the fixation device. It is appreciated that alternativemethods and techniques for detachment can be used, for example, byreleasing the distal second end of the proximal element actuator fromanchoring and retracting the delivery catheter handle as describedfurther below, e.g., FIG. 22A among others.

FIG. 16 illustrates a released fixation device 14 in a closed position.As shown, the coupling member 19 remains separated from the shaft 12 ofthe interventional tool 10 and the proximal elements 16 are deployed sothat tissue (not shown) may reside between the proximal elements 16 anddistal elements 18.

FIGS. 17A-17C illustrate a covering 100 on the fixation device 14wherein the device 14 is in various positions. FIG. 17A shows thecovering 100 encapsulating the distal elements 18 and the actuationmechanism 58 while the device 14 is in the open position. Thus, theengagement surfaces 50 are covered by the covering 100 which helps tominimize trauma on tissues and provides additional friction to assist ingrasping and retaining tissues. FIG. 17B shows the device 14 of FIG. 17Ain the inverted position. The covering 100 is loosely fitted and/or isflexible or elastic such that the device 14 can freely move to variouspositions and the covering 100 conforms to the contours of the device 14and remains securely attached in all positions. FIG. 17C shows thedevice 14 in the closed position. Thus, when the fixation device 14 isleft behind as an implant in the closed position, the exposed surfacesof the device 14 are substantially covered by the covering 100. It maybe appreciated that the covering 100 may cover specific parts of thefixation device 14 while leaving other parts exposed. For example, thecovering 100 may comprise sleeves that fit over the distal elements 18and not the actuation mechanism 58, caps that fit over the distal ends54 of the distal elements 18 or pads that cover the engagement surfaces50, to name a few. It may be appreciated that, the covering 100 mayallow any frictional accessories, such as barbs, to be exposed. Also,the covering 100 may cover the proximal elements 16 and/or any othersurfaces of the fixation device 14. In any case, the covering 100 shouldbe durable to withstand multiple introduction cycles and, when implantedwithin a heart, a lifetime of cardiac cycles.

The covering 100 may alternatively be comprised of a polymer or othersuitable materials dipped, sprayed, coated or otherwise adhered to thesurfaces of the fixation device 14. Optionally, the polymer coating mayinclude pores or contours to assist in grasping the tissue and/or topromote tissue ingrowth.

Any of the coverings 100 may optionally include drugs, antibiotics,anti-thrombosis agents, or anti-platelet agents such as heparin,COUMADIN® (Warfarin Sodium), to name a few. These agents may, forexample, be impregnated in or coated on the coverings 100. These agentsmay then be delivered to the grasped tissues surrounding tissues and/orbloodstream for therapeutic effects.

B. Fixation Device Locking Mechanisms

As mentioned previously, the fixation device 14 optionally includes alocking mechanism for locking the device 14 in a particular position,such as an open, closed or inverted position or any positiontherebetween. It may be appreciated that the locking mechanism includesan unlocking mechanism which allows the device to be both locked andunlocked. FIGS. 18-21 illustrate an embodiment of a locking mechanism106. Referring to FIG. 18, in this embodiment, the locking mechanism 106is disposed between the coupling member 19 and the base 69 of theactuation mechanism 58. The base 69 is fixedly attached to the stud 74which extends through the locking mechanism 106. The stud 74 isreleasably attached to the actuator rod 64 which passes through thecoupling member 19 and the shaft 12 of the interventional tool 10. Thebase 69 is also connected to the legs 68 of the actuation mechanism 58which are in turn connected to the distal elements 18.

FIG. 18 also illustrates the proximal elements 16, which in thisembodiment straddle the locking mechanism and join beneath the lockingmechanism 106. The proximal elements 16 are shown supported by proximalelement lines 90. The proximal elements 16 are raised and lowered bymanipulation of the proximal element lines 90. In addition, lock lines92 are shown connected with a release harness 108 of the lockingmechanism 106. The lock lines 92 are used to lock and unlock the lockingmechanism 106 as will be described below. The proximal element lines 90and lock lines 92 may be comprised of any suitable material, typicallywire, nitinol wire, cable, suture or thread, to name a few. In addition,the proximal element lines 90 and/or lock lines 92 may include acoating, such as parylene. Parylene is a vapor deposited pinhole freeprotective film which is conformal and biocompatible. It is inert andprotects against moisture, chemicals, and electrical charge.

FIG. 19 provides a front view of the locking mechanism 106 of FIG. 18.However, here the proximal elements 16 are supported by a singleproximal element line 90 which is through both of the proximal elements16. In this arrangement both of the elements are raised and loweredsimultaneously by action of a single proximal element line 90. Whetherthe proximal elements 16 are manipulated individually by separateproximal element lines 90 or jointly by a single proximal element line90, the proximal element lines 90 may extend directly through openingsin the proximal elements and/or through a layer or portion of a covering100 on the proximal elements, or through a suture loop above or below acovering 100.

FIGS. 20-21 illustrate the locking mechanism 106 showing the lockingmechanism 106 in the unlocked and locked positions respectively.Referring to FIG. 20, the locking mechanism 106 includes one or morewedging elements, such as rolling elements. In this embodiment, therolling elements comprise a pair of barbells 110 disposed on oppositesides of the stud 74, each barbell having a pair of generallycylindrical caps and a shaft therebetween. The barbells 110 and the stud74 are preferably comprised of cobalt chromium or stainless steel,however any suitable material may be used. The barbells 110 aremanipulated by hooked ends 112 of the release harness 108. When anupwards force is applied to the harness 108 by the lock line 92(illustrated in FIG. 18), the hooked ends 112 raise the barbells 110against a spring 114, as shown in FIG. 20. This draws the barbells 110up along a sidewall or sloping surface 116 which unwedges the barbells110 from against the stud 74. In this position, the stud 74 is free tomove. Thus, when the lock line 92 raises or lifts the harness 108, thelocking mechanism 106 is in an unlocked position wherein the stud 74 isfree to move the actuation mechanism 58 and therefore the distalelements 18 to any desired position. Release of the harness 108 by thelock line 92 transitions the locking mechanism 106 to a locked position,illustrated in FIG. 21. By releasing the upwards force on the barbells110 by the hooked ends 112, the spring 114 forces the barbells 110downwards and wedges the barbells 110 between the sloping surface 116and the stud 74. This restricts motion of the stud 74, which in turnlocks the actuation mechanism 58 and therefore distal elements 18 inplace. In addition, the stud 74 may include one or more grooves 82 orindentations which receive the barbells 110. This may provide more rapidand positive locking by causing the barbells 110 to settle in a definiteposition, increase the stability of the locking feature by furtherpreventing movement of the barbells 110, as well as tangible indicationto the user that the barbell has reached a locking position. Inaddition, the grooves 82 may be used to indicate the relative positionof the distal elements 18, particularly the distance between the distalelements 18. For example, each groove 82 may be positioned to correspondwith a 0.5 or 1.0 mm decrease in distance between the distal elements18. As the stud 74 is moved, the barbells 110 will contact the grooves82; by counting the number of grooves 82 that are felt as the stud 74 ismoved, the user can determine the distance between the distal elements18 and can provide the desired degree of coaptation based upon leafletthickness, geometry, spacing, blood flow dynamics and other factors.Thus, the grooves 82 may provide tactile feedback to the user.

The locking mechanism 106 allows the fixation device 14 to remain in anunlocked position when attached to the interventional tool 10 duringgrasping and repositioning and then maintain a locked position when leftbehind as an implant. It may be appreciated, however, that the lockingmechanism 106 may be repeatedly locked and unlocked throughout theplacement of the fixation device 14 if desired. Once the final placementis determined, the lock line 92 and proximal element lines 90 areremoved and the fixation device is left behind.

While the above described embodiments of the invention utilize apush-to-open, pull-to-close mechanism for opening and closing distalelements 18, it should be understood that a pull-to-open, push-to-closemechanism is equally possible. For example, distal elements 18 may becoupled at their proximal ends to stud 74 rather than to coupling member19, and legs 68 may be coupled at their proximal ends to coupling member19 rather than to stud 74. In this example, when stud 74 is pusheddistally relative to coupling member 19, distal elements 18 would close,while pulling on stud 74 proximally toward coupling member 19 would opendistal elements 18.

C. Individual Actuation of Proximal Elements

In another embodiment, with reference to FIG. 9, actuation of theproximal elements 16 may be accomplished by using one or more proximalelement lines or actuators 90. Such actuation can be achieved in variousways. For example, as shown in FIG. 22A, the proximal element actuators90A and 90B could be threaded through line loops 48A and 48B, which aredisposed on the radially outward and proximal sides of the proximalelements 16A and 16B, respectively. The distal ends of proximal elementactuators 90A and 90B may comprise closed loops 95A and 95B, whichencircle the shaft 12 and the coupling member 19 shown in FIG. 22A ascoupled together. As discussed above, the shaft 12 and the couplingmember 19 can be releasably coupled together. To have the closed loops95A and 95B surround shaft 12 and the coupling member 19, the closedloops 95A and 95B are placed over the shaft 12 and/or the couplingmember 19 prior to the coupling shaft 12 and the coupling member 19together. When the closed loops 95A and 95B encircle the shaft 12 andthe coupling member 19, the closed loops 95A and 95B hold the distalends of the proximal element actuators 90A and 90B in place relative tothe shaft 12 and the coupling member 19 and restrict the degree to whichthe proximal element actuators 90A and 90B can be retracted. By beingthreaded through the line loops 48A and 48B, the proximal elementactuators 90A and 90B are mechanically linked to the proximal elements16A and 16B, respectively. Thus, as shown in FIG. 23, when the proximalelement actuators 90A and 90B are retracted proximally in a direction96, they move the proximal elements 16A and 16B away from the distalelements 18A and 18B, respectively. Similarly, pushing the proximalelement actuators 90A and 90B distally moves the proximal elements 16Aand 16B toward the distal elements 18A and 18B.

In another embodiment, to enable the proximal element actuators 90A and90B to pull the proximal elements 16A and 16B proximally, as well aspush the proximal elements 16A and 16B distally, each of the proximalelement actuators 90A and 90B may be configured with a thin wire portion90D and a thick wire portion 90E. The thin wire portions 90D extend fromthe loops 48A and 48B to the thick wire portions 90E. This thin wireportions 90D enable the proximal element actuators 90A and 90B to beretracted through the line loops 48A and 48B when the proximal elementactuators are pulled proximally. On the other hand, the thick wireportions 90E have a stiffness that prevents these portions of theproximal element actuators 90A and 90B from passing through the loops48A and 48B as the stiffer sections cannot easily bend to make the turnrequired to extend through the loops 48A and 48B toward the shaft 12.Thus, when the proximal element actuators 90A and 90B are pushed to thepoint where the thick wire portions 90E reach the loops 48A and 48B, theproximal element actuators 90A and 90B function to push the proximalelements 16A and 16B toward the distal elements 18A and 18B,respectively.

FIGS. 59A and 59B show an embodiment in which thick wire portions 90Eare formed by rolling an end of a round thin wire portion 90D. Inparticular, the rolling of the round portion of the wire results in across section having a thick portion T3 formed as a result of rolling toreduce the round section thickness T1 to a thickness T2. This results ina substantially rectangular shaped cross section having the dimensionsT2 and T3. Notably, T3 is greater than T1 and T2 is less than T1. As aresult of this flattening of the end of the proximal element actuators90A and 90B, the bending characteristics of the end portion is changed.That is, under a compressive load, the bending will tend to occur alongthe plane of the FIG. 59A and not in the plane of FIG. 59B. The roundportion (thin) may have a diameter in the range of 0.009 to 0.012 incheswhereas the thick portion may have a width ranging from 0.013 to 0.02inches. Also, as shown in FIGS. 60A and 60B, the proximal elementactuators 90A and 90B may be formed with multiple thick portions thatthicken toward the distal end of the actuators. As shown in FIG. 60B,TA<TB<TC<TD.

In another embodiment as shown in FIG. 22B, as an alternative to using athick/thin wire combination, the proximal element actuators 90A and 90Bmay comprise a thin wire contained within an outer tube 90G. In thisembodiment, instead of relying on a stiffer thick wire portion, theproximal element actuators include an outer tube 90G to push theproximal elements 16A and 16B distally. The outer tube 90G may comprise,for example, a braided polyamide tube.

By using a thick wire portion or an outer tube, the proximal elements16A and 16B can be pushed or position distally toward the distalelements with more force. In contrast, when configured such the proximalelements 16A and 16B are biased to extend distally in combination withonly thin wire proximal element actuators 90A and 90B, the engagingforce between the proximal elements 16A and 16B and the distal elements18A and 18B decreases as the distal elements are moved distally, i.e.,such as 120-180 degrees as shown in FIG. 3B. However, when either athick wire portion or an outer tube is introduced in the proximalelements 16A and 16B, the proximal elements may be pushed distally withmore force. This provides more control and better positioning forcapturing leaflets during the coapting of the leaflets. Further, whenthere is a relatively large gap between the leaflets, having the distalelements extending in a 180 degree alignment a shown in FIG. 3B, enablesthe system to more easily capture the leaflets over this gap orseparation. Moreover, the ability to push the proximal elements 16A and16B over this range (120-180 degrees or more) to engage the distalelements 18A and 18B provides a response as well as improved geometryfor leaflet grasping.

The proximal element actuators 90A and 90B may be moved so that theproximal elements 16A and 16B are moved at a variety of angles anddistances from the distal elements 18A and 18B. And, the degree to whichthe proximal element actuators 90A and 90B are pushed or pulled can bemaintained to keep the positions of the proximal elements 16A and 16Bhave relative to the distal elements 18. For example, as shown in FIG.24, the proximal element actuators 90A and 90B are pulled proximally andmaintained in the position shown so as to maintain the proximal elements16A and 16B in an intermediate position relative to the distal elements18. This intermediate position is between a position in which theproximal elements 16A and 16B are biased toward and that in which theproximal elements 16A and 16B are fully retracted as in FIG. 23. Asshown in FIG. 27, once the proximal elements 16A and 16B are in adesired position, the shaft 12 and the coupling member 19 can bedecoupled so that proximal retraction of the proximal element actuators90A and/or 90B decouples the proximal element lines from the proximalelements 16. Thus, the fixation device 14 can be left in place while theshaft 12, the proximal element actuators 90A and 90B, and other partscan be removed from a site of operation. As shown in FIGS. 22 through28, the fixation device 14 typically includes a covering 100substantially the same as discussed in FIGS. 16A-16C below.

It may be desirable to provide for independent actuation of the proximalelements 16A and 16B. For example, as shown in FIG. 25, the proximalelement actuator 90A is proximally retracted and rotates the proximalelement 16A away from the distal element 18A, while the proximal elementactuator 90B is pushed distally and rotates the proximal element 16Btoward the distal element 18B. Similarly, as shown in FIG. 26, theproximal element actuator 90A is left alone, allowing the proximalelement 16A to maintain the position it is biased toward, while theproximal element actuator 90B is proximally retracted, moving theproximal element 16B away from the distal element 18B. Providing for theindependent actuation of the proximal elements 16A and 16B allowsleaflets to be independently grasped by the proximal elements 16A and16B and the distal elements 18A and 18B. Thus, the fixation device 14can coapt leaflets more easily and at more optimal locations. Forexample, as opposed to grasping two leaflets simultaneously, a firstleaflet can be grasped at a desired position and the fixation device 14can then be repositioned so that a second leaflet can be grasped at amore optimal position.

With reference to FIGS. 61-64B for purpose of illustration and notlimitation, a variety of regurgitant mitral valve etiologies can benefitfrom independent leaflet capture or sequential leaflet capture. FIG. 61,for example, shows a heart having functional mitral regurgitation with arestricted and short posterior mitral leaflet (PML). Simultaneouscapturing both the anterior mitral leaflet (AML) and the PML can bedifficult due to one or more of the limited mobility of the PML, shortlength of the PML, wide gap between the leaflets, and a high tetheringforce transmitted by the subvalvular structures, such as the chordaenetwork and associated papillary muscle(s). Independent leaflet capturecan be used to (1) first capture the PML without concern forsimultaneously capturing the AML (FIG. 62A), (2) reposition the cathetergently to a position for capture of the AML while retaining capture ofthe PML (FIG. 62B), and (3) capture the AML. The sequence can bereversed or adapted based on which leaflet is observed by the operatorto be more challenging or particularly immobile during the cardiaccycle.

FIGS. 63A-B, for example, show a heart with a degenerative mitralregurgitation flail scenario where the PML is flailing excessively, butthe AML chordae support network is intact. In this case, the AML havingintact chordae moves more centrally under systolic pressure (FIG. 63A),due to its edge angle. Therefore, AML capture can be easier and moreeffective during systolic phase when the leaflet edge moves inward anddeeper into an implantable fixation device 14 (not shown) positionedbetween the leaflets. During systole, however, the flailing PML isuntethered from the chordae and can flail uncontrollably into the leftatrium. Accordingly, PML leaflet capture is more challenging during thesystolic phase of the cardiac cycle. In contrast, in the diastolic phase(FIG. 63B), the flailing PML can be pushed downward. This position canbetter facilitate capturing a maximum amount of the leaflet. As such, inthis scenario AML capture can be performed during cardiac systole (FIG.64A), and PML capture can be performed during cardiac diastole (FIG.64B).

Alternatively, leaflets may be still be simultaneously grasped ifdesired as the independently actuatable proximal element actuators canstill be moved simultaneously. Also, after leaflets are grasped, theycan be released and the leaflets can be grasped again, for example, ifthe leaflets are malcoapted at the first grasp. The embodimentsdescribed about may be utilized with either the s-lock or the l-lockconfigurations described herein.

Embodiments of the fixation device similar to the devices describedabove may include both a gripper pusher 81 and independently actuatableproximal elements 16A and 16B, as shown for example in FIG. 28. Havingboth a gripper pusher 81 and independently actuatable proximal elements16A and 16B may allow the fixation device to have many of the advantagesdescribed above such as to more accurately and more strongly graspleaflets.

In another embodiment, the proximal element actuators 90A and 90B mayeach comprise a continuous loop that enters and exits the nose 318 ofthe shaft 302 as shown in FIG. 18. However, as shown in FIGS. 29-33, theproximal element actuators 90A and 90B may be coupled with the releaseharness 108 so that the lock lines 92 may be eliminated.

FIG. 29 illustrates a configuration in which the proximal elementactuator 90A is looped through the end of proximal element 16A and therelease harness 108. The other proximal element actuator 90B is loopedonly through the proximal element 16B. Thus, manipulation of theproximal element actuator 90A in this embodiment will actuate theproximal element 16A either proximally or distally to engage ordisengage with tissue. After the tissue engagement is completed and theleaflets are properly coapted, the proximal element actuator 90A may befurther actuated to release the release harness 108 of the lockingmechanism 106. On the other hand, if it determined that the fixationdevice 14 requires repositioning, applying tension on the proximalelement actuator 90A will unlock the locking mechanism. Furtheractuation of the proximal element actuator 90A may then cause theproximal element 16A to disengage from the leaflet so that repositioningcan be performed.

In another embodiment, as illustrated in FIG. 30, the proximal elementactuators 90A and 90B may be configured to cross the shaft 12 to providebetter leverage for actuation. Again, in this configuration the proximalelement actuator 90A is looped through the end of proximal element 16Aand the release harness 108. The other proximal element actuator 90B islooped only through the proximal element 16B. However, crossing theshaft in this manner changes the angular relationship between the pointwhere the proximal element actuators 90A and 90B exit the nose 318 ofthe shaft 302 and where they connect to a corresponding proximal element16A and 16B. As such, the resultant force of actuation on the proximalelements 16A and 16B is increased for a given amount of tension on theproximal element actuators 90A and 90B as shown in the configuration ofFIG. 29. This arrangement also allows for elimination of the lock lines92. As illustrated in FIG. 29, each of the proximal element actuators90A and 90B may straddle the shaft 12. However, the lines may also berouted to cross on the same side of the shaft 12.

FIG. 31 shows another configuration of routing the proximal elementactuators 90A and 90B. In this configuration, the proximal elementactuator 90A and proximal element actuator 90B are each coupled with theone of the proximal elements 16A and 16B and the release harness 108.While the embodiment shown in FIG. 30 locks the fixation device 14 onlyafter the proximal element 16A is moved into an engagement position witha leaflet, the configuration of FIG. 31 permits the operator to controlthe sequence of leaftlet engagement between proximal elements 16A and16B. In other words, the proximal element actuator 90A need not beactuated after locking the fixation device 14 in the event an operatormerely elects to actuate proximal element 16B.

FIGS. 32 and 33 illustrate another possible configuration for theproximal element actuators 90A and 90B. Each proximal element actuatorcomprises a loop that exits from and returns to the nose 318. However,in this case, the proximal element actuators 90A and 90B are each doublethreaded through the end of a corresponding one of the proximal elements16A and 16B and then looped around the release harness 108. In FIG. 32the proximal element actuator 90A exits the nose 318 on a side of thenose 318 adjacent to the proximal element 16A and the proximal elementactuator 90B exits the nose 318 on a side of the nose 318 adjacent tothe proximal element 16B. In an alternative configuration, the proximalelement actuator 90A exits the nose 318 on a side of the nose 318opposite to the proximal element 16A and the proximal element actuator90B exits the nose 318 on a side of the nose 318 opposite to theproximal element 16B. Crossing the shaft in this manner changes theangular relationship between the point where the proximal elementactuators 90A and 90B exit the nose 318 of the shaft 302 and where theyconnect to a corresponding proximal element 16A and 16B. As such, theresultant force of actuation on the proximal elements 16A and 16B isincreased for a given amount of tension on the proximal elementactuators 90A and 90B.

In each of the embodiments of FIGS. 29-33, each of the proximal elementactuators 90A and 90B may be formed of a single line, which may beformed of a single or multiple filaments, that extends from and returnsto the nose 318 of the shaft 302. However, in the embodiments of FIGS.32 and 33, the proximal element actuators 90A and 90B may only extendfrom the nose 318 and then terminate at the coupling shaft 12 or thecoupling member 19 as shown in FIG. 24.

D. Individual Actuation of Proximal Elements/Single Actuator

In other embodiments, sequential grasping may be accomplished by use ofa single actuator. FIG. 34 illustrates a configuration wherein a singleproximal element actuator 90, having a proximal end and a distal end,extends from the nose 318 of the shaft 302 to one of the proximalelements 16A. It may be looped through an eyelet at a distal end of theproximal element 16A or held by a suture at the same location. The sameproximal element actuator 90 then extends across the coupling shaft 12to the other proximal element 16B where it is coupled to the distal endof this proximal element 16b in a manner similar to proximal element16A. The distal end of this proximal element actuator 90 extends toeither of the coupling shaft 12 or the coupling member 19 where it issecured. In FIG. 34 it is secured using a loop. However, the proximalelement actuator may be releasable fixed to the fixing device 14 inaccord in any of the embodiments disclosed below.

By virtue of the geometry of this configuration, each proximal element16A and 16B may be independently actuated and the proximal elementactuator 90 may be released in tandem with the separation of thecoupling member 19. As illustrated in FIG. 35, due to the manner ofrouting the proximal element actuator 90, the resultant forces F1 and F2are at different angles. These resultant forces and their directions arebased on the tension on the proximal element 90 and the direction(angle) at which the proximal element actuator 90 approaches and extendsaway from a corresponding proximal element 16A or 16B. The force thatcauses a corresponding proximal element to move is the component of theforce that is perpendicular to the length of a corresponding proximalelement. This perpendicular component is represented by FN1 and FN2. Asmaller angle (θ₁, θ₂) between the resultant force and the perpendicularcomponent leads to a larger perpendicular component. As illustrated inFIG. 35, because the angle θ₁ is smaller than the angle θ₂, theperpendicular component FN1 will be larger than the perpendicularcomponent FN2. Accordingly, for a given amount of tension in theproximal element actuator 90, proximal element 16A will receive moremoving force than proximal element 16B. That means that proximal element16B will remain closed as proximal element 16A opens, and proximalelement 16B will open after proximal element 16A is fully opened. Thisallows for independent actuation of the proximal elements 16A and 16Busing a single proximal element actuator 90.

E. Gripper Pusher to Engage Proximal Elements

In some situations, the valve leaflets may fully or partially detachfrom the fixation device due to poor leaflet insertion between theproximal and distal elements. Evaluation of valve leaflet insertion inthe fixation device is therefore performed using standard imagingtechnology such as echocardiography and fluoroscopy. However, dependingon the angle and/or position of the proximal and distal elementsrelative to the delivery catheter, it can be challenging to assess thedepth of valve leaflet insertion into the fixation device, or todifferentiate between the leaflets and the proximal and distal elementsof the fixation device. Visualization is therefore preferably performedwith the distal elements in a more open configuration with the distalelements displaced from one another. However, since many currentembodiments of the fixation device only permit the proximal elements toopen up to an included angle of about 85°, the distal elements thereforemust be closed up to an included angle of between about 45° andpreferably 60° in order securely grasp the valve leaflets between theproximal and distal elements. While this configuration helps an operatorvisualize and differentiate between the valve leaflets and the fixationdevice, it is preferable to further open up the distal elements to anincluded angle of greater than 90°, and more preferably to 120° or more.Thus, it would be desirable to modify the proximal elements to open upfurther.

FIGS. 36-40 illustrate an embodiment of a fixation device similar to thedevice of FIGS. 7A-14, with a major difference being that thisembodiment includes a gripper pusher. FIG. 36 illustrates fixationdevice 14 that generally takes the same form as fixation device 14previously described. In addition to the features previously described,fixation device 14 also includes a gripper pusher 81. The gripper pusher81 deflects radially outward resulting in a bowed region 83 that expandsoutward until the bowed region 83 engages a superior surface of theproximal elements 16. As the bowed region 83 continues to deflectradially outward, it further pushes on the proximal elements 16 suchthat the proximal elements are deflected and rotated outward toward theengagement surface of the distal elements 18. Thus, the proximalelements 16 may be deflected outward further than they normally would,and therefore the valve leaflets may be captured between the proximaland distal elements when the distal elements are disposed in a more openposition with a larger included angle therebetween. In preferredembodiments, the included angle between the distal elements is greaterthan about 90°, preferably greater than about 110°, and more preferablygreater than about 120°. In the embodiment of FIG. 36, the gripperpusher 81 includes two arms formed from a metal, polymer or otherwire-like material. Exemplary materials include cobalt chromium alloy,stainless steel, nitinol, and the like. Polymers may also be used tofabricate the gripper pusher. The gripper pusher 81 may be actuated tobow outwards upon application of an axially oriented compressive forcethat is generally parallel to the longitudinal axis of the gripperpusher arms. During compression, the gripper pusher bows outward formingbowed region 83. In other embodiments, the gripper pusher may be aspring which is resiliently biased to bow outward forming bowed region83. However, when proximal element lines (not illustrated here) aretensioned to lift the proximal elements 16, the gripper pusher springswill collapse to a reduced profile.

FIG. 37 illustrates the fixation device 14 having a covering for tissueingrowth, and with the gripper pusher 81 expanded such that the proximalelements 16 (also referred to as gripping elements) are in engagementwith the distal elements 18 (also referred to as fixation elements). Thevalve leaflets (not shown for convenience) are pinched therebetween.FIG. 38 illustrates the gripper pusher 81 in the collapsedconfiguration. The bowed region 83 collapses, allowing the proximalelements 16 to retract towards shaft 12, allowing the valve leaflets(not shown) to be released from the fixation device 14. The gripperpusher 83 is offset from the proximal elements 16 so that the proximalelements can retract without interfering with the gripper pusher 81.

FIG. 39 highlights the gripper pusher 83 which preferably includes twospring arms 99. Each arm 99 is formed from wire or machined from a sheetor other stock material and in this embodiment has a rectangularcross-section, although other cross-sections are also contemplated. Adistal portion 91 of each arm 99 has a notched region 93 forming a pairof fingers that can engage with a boss or other attachment mechanism onthe fixation device. The notch may be released from the boss when thefixation device 14 is detached from the delivery catheter shaft 12.Additionally, each arm includes two bowed regions, or peaks, including alarger distal bowed region 83, and a smaller proximal bowed region 95.The larger bowed region 83 flares outwardly a greater distance so as toengage and push the proximal elements 16 into engagement with the distalelements 18. When the distal bowed region 83 relaxes and collapses awayfrom the proximal elements 16, or when collapsed by retraction of theproximal elements, the smaller proximal bowed regions 95 expand radiallyoutward. An attachment ring or coupling collar 97 is adjacent nose 318(described in greater detail below) and is slidably disposed over theshaft 12 and allows coupling of the gripper arms 99 to the shaft 12.FIG. 40 illustrates the distal bowed region 83 in engagement with theproximal elements 16, and also illustrates engagement of the notch 93 onthe distal portion of each arm 99 with a boss 94 on the fixation device14.

As described above, for example, with reference to FIGS. 10A through11B, actuation of the proximal elements 16 may be accomplished by usingone or more proximal element lines or actuators 90. In anotherembodiment, this actuation can be achieved by combination of theproximal element actuators 90 and the gripper pusher 81 as set forthabove. For example, as shown in FIG. 41, the proximal element actuators90A and 90B could be threaded through line loops 48A and 48B, which aredisposed on the radially outward and proximal sides of the proximalelements 16A and 16B, respectively. The distal ends of proximal elementactuators 90A and 90B may comprise closed loops 95A and 95B, whichencircle the shaft 12 and the coupling member 19 shown in FIG. 41 ascoupled together. As discussed above, the shaft 12 and the couplingmember 19 can be releasably coupled together. To have the closed loops95A and 95B surround shaft 12 and the coupling member 19, the closedloops 95A and 95B are placed over the shaft 12 and/or the couplingmember 19 prior to the coupling shaft 12 and the coupling member 19together. When the closed loops 95A and 95B encircle the shaft 12 andthe coupling member 19, the closed loops 95A and 95B hold the distalends of the proximal element actuators 90A and 90B in place relative tothe shaft 12 and the coupling member 19 and restrict the degree to whichthe proximal element actuators 90A and 90B can be retracted. By beingthreaded through the line loops 48A and 48B, the proximal elementactuators 90A and 90B are mechanically linked to the proximal elements16A and 16B, respectively. Thus, as shown in FIG. 42, when the proximalelement actuators 90A and 90B are retracted proximally in a direction96, they move the proximal elements 16A and 16B away from the distalelements 18A and 18B, respectively.

However, in combination with the proximal element actuators 90A and 90B,which permit independent actuation of the proximal elements 16A and 16B,the gripper pusher 81 may also be included in the fixation device. Thus,the proximal elements 16A and 16B may be deflected outward further thanthey normally would, and therefore the valve leaflets may be capturedbetween the proximal and distal elements when the distal elements aredisposed in a more open position with a larger included angletherebetween. In preferred embodiments, the included angle between thedistal elements is greater than about 90°, preferably greater than about110°, and more preferably greater than about 120°. Thus, in thisembodiment, the fixation device is capable for independent actuation aswell as a wide range of proximal element 16A and 16B movement.

The proximal element actuators 90A and 90B may be moved so that theproximal elements 16A and 16B are moved at a variety of angles anddistances from the distal elements 18A and 18B. And, the degree to whichthe proximal element actuators 90A and 90B are pushed or pulled can bemaintained to keep the positions the proximal elements 16A and 16B haverelative to the distal elements 18. For example, as shown in FIG. 43,the proximal element actuators 90A and 90B are pulled proximally andmaintained in the position shown so as to maintain the proximal elements16A and 16B in an intermediate position relative to the distal elements18. This intermediate position is between the position in which theproximal elements 16A and 16B are biased toward and that in which theproximal elements 16A and 16B are fully retracted as in FIG. 42. Asshown in FIG. 46, once the proximal elements 16A and 16B are in adesired position, the shaft 12 and the coupling member 19 can bedecoupled so that proximal retraction of the proximal element actuators90A and/or 90B decouples the proximal element lines from the proximalelements 16. Thus, the fixation device 14 can be left in place while theshaft 12, the proximal element actuators 90A and 90B, and other partscan be removed from a site of operation. As shown in FIGS. 41 through47, the fixation device 14 typically includes a covering 100.

It may be desirable to provide for independent actuation of the proximalelements 16A and 16B. For example, as shown in FIG. 44, the proximalelement actuator 90A is proximally retracted and rotates the proximalelement 16A away from the distal element 18A, while the proximal elementactuator 90B is pushed distally and rotates the proximal element 16Btoward the distal element 18B. Similarly, as shown in FIG. 45, theproximal element actuator 90A is left alone, allowing the proximalelement 16A to maintain the position it is biased toward, while theproximal element actuator 90B is proximally retracted, moving theproximal element 16B away from the distal element 18B.

In another embodiment as illustrated in FIG. 47, the independentactuation of the proximal elements 16A and 16B is performed in a mannersimilar to the embodiment depicted in FIG. 46. However, as shown in FIG.47, the proximal element actuators 90A and 90B are formed of a doubleloop configuration. Each proximal element actuator 90A and 90B exits theand returns through the nose 318 of the shaft 302 after being routedthrough the distal end of a corresponding one of the proximal elements16A and 16B, and looped around the shaft 12 or coupling mechanism 19.This configuration provides the similar operational flexibility as theembodiment illustrated in FIG. 46, but permits removal of the proximalelement actuators 90A and 90B before the coupling mechanism 19 isreleased from the shaft 12.

In another embodiment as illustrated in FIG. 48, a single proximalelement actuator 90 is configured to perform sequential grasping in asimilar manner to the embodiment depicted in FIG. 34. However, thisembodiment also utilizes the gripper pusher 81 to provide for anextended range of movement in the open direction of the distal elements18A and 18B. By virtue of the geometry of this configuration, eachproximal element 16A and 16B may be independently actuated and theproximal element actuator 90 may be released in tandem with theseparation of the coupling member 19. As illustrated in FIG. 35, due tothe manner of routing the proximal element actuator 90, the resultantforces F1 and F2 are at different angles. These resultant forces andtheir directions are based on the tension on the proximal element 90 andthe direction (angle) at which the proximal element actuator 90approaches and extends away from a corresponding proximal element 16A or16B. Again, the force that causes a corresponding proximal element tomove is the component of the force that is perpendicular to the lengthof a corresponding proximal element. This perpendicular component isrepresented by FN1 and FN2. Accordingly, for a given amount of tensionin the proximal element actuator 90, proximal element 16A will receivemore moving force than proximal element 16B. That means that proximalelement 16B will remain closed as proximal element 16A opens, andproximal element 16B will open after proximal element 16A is fullyopened. This allows for independent actuation of the proximal elements16A and 16B using a single proximal element actuator 90. Additionally,however, in this embodiment, the included angle between the distalelements may greater than about 90°, preferably greater than about 110°,and more preferably greater than about 120°. Thus, in this embodiment,the fixation device is capable for independent actuation as well as awide range of proximal element movement.

F. Coupling of Proximal Element Actuator

In many of the embodiments described above, the proximal elementactuator 90 or proximal element actuators 90A and 90B includes an endthat may be releasable coupled to the fixation device 14. Describe beloware multiple embodiments showing various methods and structures forreleasably coupling the proximal element actuators that may be appliedto any of the embodiments described above.

In many embodiments, the shaft 12 and the coupling member 19 arereleasably coupled together via an L-locking mechanism. For example, asshown in FIG. 49A, the proximal element actuator 90 may comprise a roundT-shaped end 90T distal of the flat section 90F and the shaft 12 maycomprise L-shaped ends 12L. As shown in the perspective view of FIG.49B, the proximal element actuator 90 is releasably coupled to thecoupling member 19 when it and shaft 12 are placed into the channel 19Cof the coupling member 19. As the shaft 12 is placed through the channel19C, the L-shaped ends 12L are forced inwardly until they reachapertures 19A. At that point, the L-shaped ends 12L expand outwardly tofit into the apertures 19A, thereby locking the shaft 12 in placerelative to the coupling member 19, as shown in cross-sectional view ofFIG. 49C. The round T-shaped distal end 90T will typically be placed inthe space 19CA prior to the shaft 12 being placed in the channel 19C. Asshown in FIG. 49C, the round T-shaped distal end 90T then becomestrapped in the space or pocket 19CA between the channel 19C and a widerportion of the shaft 12 when the shaft is placed therein. OtherL-locking or other locking mechanisms are described in commonly assignedU.S. patent application Ser. No. 12/393,452 entitled “DetachmentMechanism for Implantable Fixation Devices” and filed Feb. 26, 2009, thefull contents of which are incorporated herein by reference.

The round T-shaped end 90T of the proximal element actuator 90 may alsobe used to facilitate releasably coupling the proximal element line 90to the shaft 12 and coupling member 19 is many other ways. For example,as shown in FIG. 50A, the L-shaped end 12L of the shaft 12 may compriseat least one proximal element line slot 12S. As shown in FIGS. 50C and50D, the T-shape end 90T of the proximal element actuator 90 is slidinto the proximal element line slot 12S. Then, the shaft 12 is placedinto the coupling member 19, thereby also locking the proximal elementline 90 in place. As shown in FIG. 50E, removing the shaft 12 from thecoupling member 19 allows the proximal element line 90 to be slid out ofthe proximal element line slot 12S of L-shaped end 12L, therebydecoupling the proximal element actuator 90 from both the shaft 12 andthe coupling device 19.

As shown in FIG. 51A, the proximal element actuator 90 may comprise aflat T-shaped end 90TF. The shaft 12 may further comprise an innerdistal covering 1511 surrounding a distal portion of the shaft 12 and anouter distal covering 1521 surrounding the inner distal covering. Theinner distal covering 1511 will typically be in a fixed positionrelative to the shaft 12 while the outer distal covering will bemoveable relative to the shaft 12 at a range determined by tabs 1515 ofinner distal covering 1511 placed through side channels 1525 of theouter distal covering 1521. To releasably couple the proximal elementactuator 90 to the shaft 12 and coupling line 19, the T-shaped end 90TFis fit into a T-shaped cutout 1513 of inner distal covering 1511, andwhen the shaft 12 is placed into the coupling device 19, the couplingdevice 19 pushes the outer distal covering 1521 over the inner distalcovering 1511 to cover the T-shaped cutout 1513 as well as the T-shapedend 90TF, as shown in FIG. 51B. This compresses a coil spring 1522placed between the inner distal covering 1511 and the outer distalcovering 1521. When the fixation device 14 is released from the shaft12, the outer distal covering 1521 moves distally due to the action ofthe coil spring 1522 to expose the T-shape cutout 1513 to release theproximal element actuator. In some embodiments, the outer distalcovering 1521 may be spring loaded against the inner distal cover 1523so that tend to maintain their relative positions shown in FIG. 51B.

Proximal element actuators 90 may be releasably coupled to the fixationdevice 14 in a variety of ways using variations of inner and outerdistal collars over the distal portion of shaft 12, for example, asshown in FIGS. 52A to 52G. FIG. 52A shows an inner distal collar 1511Ahaving a pair of T-shaped cutouts 1513 and a tab 1514. FIG. 52B shows anouter distal collar 1521A having a channel 1524. The channel 1524 guidesthe inner distal collar 1511A via its tab 1514 as the inner distalcollar 1511A is slid into the outer distal collar 1521A, for example asshown in FIGS. 52C through 52E. As in the embodiment shown in FIGS. 51Aand 51B, to releasably couple the proximal element actuators 90 to theshaft 12 and coupling member 19, the T-shaped end 90TF is fit into aT-shaped cutout 1513 of inner distal collar 1511S. When the shaft 12 isplaced into the coupling device 19, the coupling member 19 pushes theouter distal collar 1521S over the inner distal collar 1511S to coverthe T-shaped cutout 1513 as well as the T-shaped end 90TF, as shown inFIGS. 52F and 52G. This compresses the coil spring 1522A shown in FIG.52C. When the fixation device 14 is released from the shaft 12, theouter distal covering 1521A moves distally due to the action of the coilspring 1522A to expose the T-shape cutout 1513A to release the proximalelement actuator 90.

In other embodiments, the proximal element actuators 90 may bereleasably engaged with structures that are activated by removal of theactuator rod 64 that passed through the coupling member 19 and the shaft12. As illustrated in FIG. 53 a stud 74 is releasably attached to theactuator rod 64 which passes through the coupling member 19 and theshaft 12 of the interventional tool 10. In this way, the actuator rod 64is connectable with the fixation device and acts to manipulate thefixation device, typically opening and closing the distal elements.After the leaflets have been coapted, the actuator rod 64 is removedproximally from the stud 74 to release the coupling member 19, oralternatively, the L-lock mechanism described above. In the followingembodiments, this action of the actuator rod 64 may be utilized torelease the proximal element actuators 90.

In one embodiment, as illustrated in FIGS. 54A through 54D and 55Athrough 55, spring members 331 are utilized in combination with theactuator rod 64 to hold and release the proximal element actuators 90.As shown in FIG. 54A, a portion of the shaft extending from the nose 318has two windows 333 formed therein. Two spring members are positioned onthe periphery of the shaft 12 adjacent a corresponding window so that abent portion 335 extends into the actuator rod pathway formed within theshaft 12. A proximal side of these bent portions 335 may be fixed to thenose 318 or an external portion of the shaft 12. A distal side of eachbent portion 335 is attached to a “C” shaped portion having a notch 339formed at each end of the “C” shape. The corresponding end portions ofone “C” shape portions on one spring are configured to abut the endportions of another spring so that the corresponding notches 339 canrestrict the movement of a ball 337 at the end of either one of theproximal element actuators. FIG. 54C illustrates a position in which the“C” shaped portions are in contact to form a notch that prevents distalmovement of the ball 337.

As illustrated in FIG. 55A, the actuator rod 64 is configured to have atapered profile having a narrow portion and a wide portion. As theactuator rod 64 is moved proximally in FIG. 55B, a wide portion of theactuator rod 64 contacts the bent portions 335 to separate thecorresponding “C” shaped portions of the adjacent spring members 331.This opens the notches 339 so that the ball 337 of the proximal actuator90 is released as shown in FIG. 55C.

In another embodiment as illustrated in FIGS. 56A and 56B, the proximalelement actuator 90 or proximal element actuators 90A and 90B may bereleasably attached to the shaft 12 by using one or a set of liners 65hingedly attached to the shaft 12. In this configuration, a pair ofwindows 33 (only one window is required in the case of a single proximalelement actuator) is formed in the shaft 12. A liner is hingedlyattached to the inside of the shaft 12 on a proximal side of each of thewindows 33. As shown in FIG. 56A, when the actuator rod 64 is withdrawnproximally, the liners 65 move inwardly such that the proximal elementactuators 90 are free to move. When the actuator rod 64 is in thisposition, the proximal element actuators 90 may be inserted into, orwithdraw from, the windows 33. On the other hand, when the actuator rod64 is moved distally as shown in FIG. 56B, the liners 65 are pressedoutwardly against the inside surface of the shaft 12 to trap or pinchthe proximal element actuators. This secures the proximal elementactuators so that the proximal elements 16 can be moved independently.The proximal element actuators 90 are fixed to the shaft 12 until theactuator rod 64 is again moved proximally to the position shown in FIG.56A.

Referring to FIGS. 65A-I, for purpose of illustration and notlimitation, actuator rod 64 can be used as an anchor to restrictproximal movement of the proximal element actuators 90A and 90B. Asdisclosed above, the second end (e.g., distal end portion) of proximalelement actuators 90A and 90B can each include a catch element, forexample ball 337A (see FIG. 65F) or other shapes, such as trumpet 338A(see FIG. 65D) having a cone shape, which can be sized to be receivedwithin shaft 12. As shown in FIGS. 65A-65C, a portion of the shaft 12extending from the nose 318, and proximal of the L-shaped ends 12L ofthe L-lock, can have two slots 401A and 401B defined therein. Slot 401Acan define holes 402A and 402B and slot 401B can define holes 402C and402D. Holes 402A and 402C can be sized to receive trumpets 338A and 338B(not shown), respectively, therethrough and into slots 401A and 401B,respectively. Holes 402B and 402D can be sized to prevent trumpets 338Aand 338B, respectively, from extending beyond slots 401A and 401B,respectively. The configuration of slots 401A and 401B and holes402A-402D can allow for easier manufacture of the features in shaft 12.Slots 401A and 401B can be drilled to ensure that the slots 401A and401B do not pass the entire way through shaft 12. In this configuration,trumpets 338A and 338B of proximal element actuators 90A and 90B can bemaintained within shaft 12 to manage the slack of proximal elementactuators 90A and 90B.

The trumpet 338A of proximal element actuator 90A can be inserted intoslot 401A through hole 402A and toward hole 402B, and trumpet 338B ofproximal element actuator 90B can be inserted into slot 401B throughhole 402C and toward hole 402D prior to the insertion and coupling ofthe actuator rod 64 (which passes through shaft 12) with stud 74 of thefixation device. With the actuator rod 64 passed through the shaft 12,the movement of trumpets 338A and 338B, and therefore the proximalelement actuators 90A and 90B, can be restricted. For example, trumpets338A and 338B can be inhibited from being advanced through holes 402Band 402D, respectively, and can be prevented from being pulled pastactuator rod 64 and through holes 402A and 402C, respectively.Accordingly, the second end portions of the proximal element actuators90A and 90B can be held in place relative the shaft 12. Once theactuator rod 64 is decoupled from stud 74 and subsequently retracted,movement of the trumpets 338A and 338B at the distal end portions ofproximal element actuators 90A and 90B is no longer restricted and theproximal element actuators 90A and 90B are free to move. Upon proximalretraction, the proximal element actuators 90A and 90B can threadthrough holes 402A and 402C, respectively, and decouple from theproximal elements 16A and 16B, respectively.

In accordance with the disclosed subject matter, the slots 401A and 401Bcan be drilled at an angle towards the distal end of shaft 12 (see FIGS.65E and 65G), e.g., with one hole 402B formed distal to the other hole402A on one side and one hole 402D formed distal to the other hole 402Con the other side. This configuration of slots 401A and 401B can provideeasier deployment of the proximal element actuators 90A and 90B and canreduce friction.

Hole 402A can be provided with fillet radius 403A (see FIGS. 65B and65H) and Hole 402C can be provided with fillet radius 403B (not shown)that can limit sharp edges on holes 402A and 402C and can allow theproximal element actuators 90A and 90B to curve gently on the filletradius 403A and 403B. Accordingly, fillet radius 403A and 403B canreduce tight and abrupt curvature of the proximal element actuators 90Aand 90B. The fillet radius 403A and 403B can also reduce localizedbending strain and failure due to pulling the proximal element actuators90A and 90B too hard or multiple cycles of use. The fillet radius 403Aand 403B can be at least 0.001 inch. The fillet radius can be at least20% of the proximal element line 90A and 90B diameter. In accordancewith the disclosed subject matter, the fillet radius can be at least 10%of the exit hole size. The fillet radius 403A and 403B can extend aroundthe entire respective hole 402A and 402C or can extend along a proximaledge where the proximal element actuator 90A and 90B will engage whenpulled proximally. Additionally or alternatively, holes 402A and 402Ccan be provided with a chamfer 403C with smoothed corners 403D and 403E(see FIG. 65I), which limit the bending of the proximal elementactuators 90A and 90B when pulled proximally.

Additionally or alternatively, an angle-reduction feature 405 can beprovided on the outer surface of shaft 12. For example, angle-reductionfeature 405 can include an O-ring or a metal ring and can be provided onthe outer diameter of the shaft 12, which can limit the bending of theproximal element actuators 90A and 90B when pulled in tension.

As disclosed herein and previously discussed, an additional sleeve canbe provided. The sleeve (not shown) can be disposed over the distalangled hole entry locations and can ensure the catch element remainsbetween the mandrel and the sleeve, and can control slack duringclosure.

Prior to securing the second end of each proximal element actuator withthe shaft, each proximal element actuator can be coupled with arespective proximal element. For example and with reference to FIGS.22A, 27, and 53, each proximal element actuator can include a first endportion, a second end portion, and an intermediate portion between thefirst end portion and the second end portion. Proximal element actuators90A and 90B can be coupled to the proximal elements 16A and 16B,respectively, at an intermediate portion of the proximal elementactuator, thus, when the proximal element actuators 90A and 90B areactuated proximally, the proximal element actuators 90A and 90B can movethe proximal elements 16A and 16B relative the arms 53A and 53Brespectively, thereby moving the first and second proximal elements 16Aand 16B between first and second positions.

Alternatively, and as described with respect to FIGS. 29-34, theproximal element actuators 90 can extend distally through the at leastone lumen and back proximally through the at least one lumen. Inaccordance with the disclosed subject matter, a variety of catheterconfigurations can be provided. For example, the at least one lumen caninclude at least a first proximal element actuator lumen and a secondproximal element actuator lumen. The at least one lumen can include atleast a third proximal element actuator lumen and a fourth proximalelement actuator lumen. The delivery device further can include a shaftextending through the at least one lumen, the shaft releasably coupledto a coupling member of the implantable fixation device.

With reference to FIGS. 66A-D, for purpose illustration and notlimitation, each proximal element actuators 90A and 90B can define aloop 95C and 95D, respectively, extending from the distal end portion ofthe catheter. The loops 95C and 95D can each encircle the actuator rod64. As discussed above with respect to FIGS. 66A and 66B, a portion ofthe shaft 12 extending from the nose 318 can have two windows 33 formedtherein. Loops 95C and 95D can each pass through a respective window 33formed within shaft 12, such that each loop can encircle the actuatorrod 64. Once the fixation device 14 is in a desired position, theactuator rod 64 can be decoupled from stud 74 and retracted, andsubsequent proximal retraction of the proximal element actuators 90A and90B will then decouple proximal element actuators 90A and 90B from theproximal elements 16A and 16B. Alternatively, a single window 33 can beprovided and each loop 95C and 95D can be disposed through the window 33and looped around actuation rod 64.

Alternatively, the proximal element actuators 90A and 90B can eachinclude a loop 95A and 95B, respectively, at a second end portion (suchas described in detail above with regard to the exemplary embodiments ofFIGS. 22A-B and 27). In this manner, each loop 95A and 95B can bedisposed through a respective window 33 and looped around actuator rod64. This configuration can provide similar operational flexibility asthe embodiment illustrated in FIG. 27, but permits removal of theproximal element actuators 90A and 90B before shaft 12 and couplingmember 19 are decoupled. Alternatively, a single window 33 can beprovided and each loop 95A and 95B can be disposed through the window 33and looped around actuation rod 64.

As further embodied herein, each proximal element actuator can be formedof single or multiple filaments, that extends from and returns to thenose 318 of the shaft 302. As shown in FIG. 67, for example, proximalelement actuators 90A and 90B (wherein only proximal element actuator90A is depicted for clarity) can have a second end releasably attachedto the nose 318 of the shaft 302 by using one or more proximal elementactuator mandrels 404. In this configuration, proximal element actuatormandrels 404 can extend from the proximal end portion of interventionaltool 10 to the nose 318 of shaft 302 through lumens 406, such thatproximal element actuator mandrel 404 can be manipulated by the useroutside the patient's body. For example, the distal end portion of theproximal element actuator mandrel 404 can include a plunger 408 that islarger in diameter than the diameter of lumen 406 such that proximalmovement of proximal element actuator mandrel 404 can press plunger 408against the distal surface of nose 318 of shaft 302. As disclosed hereina single actuator mandrel and plunger can be used or two or moreactuator mandrels and plungers, each coupled to a respective proximalelement actuator. Each proximal element actuators 90A and 90B (notshown) can extend from nose 318 and be coupled at an intermediateportion therefore to a respective proximal element 16A (and 16B, notshown), for example, through the actuator loops 48A (and 48B, not shown)of proximal elements 16A and 16B. The proximal element actuators secondend portion is secured to nose 318 of shaft. That is, by moving proximalelement actuator mandrels 404 distally, the distal ends of proximalelement actuators 90A and 90B each can be placed between the distalsurface of nose 318 of shaft 302 and the proximal surface of arespective plunger 408 such that proximal movement of each proximalelement actuator mandrel 404 traps or pinches the respective proximalelement actuators. As disclosed herein a single actuator mandrel andplunger can be used or two actuator mandrels and plungers, each plungercoupled to a respective proximal element actuator, can be used. This cansecure the proximal element actuators such that the proximal elements 16can be moved and released independently. After deployment of proximalelements, the respective proximal actuators can be detached by distalmovement of the proximal element actuator mandrels 404 to allow eachproximal element actuators 90 to be release and decoupled from therespective proximal elements.

Additionally or alternatively, and referring to FIG. 68, for purpose ofillustration and not limitation, and wherein only proximal elementactuator 90A is depicted for clarity, the distal end of the proximalelement actuator mandrel 404 can include a blade 410 fixedly attached toits distal end portion. Proximal element actuator mandrel 404 can berotatable with respect to shaft 302, thereby making blade 410 rotatablewith respect to shaft 302. Rotation of proximal element actuator mandrel404 thus can deploy blade 410 to cut the respective proximal elementactuator 90. For example, each proximal element actuator 90 can becoupled to the nose 318 of the shaft 302 to form a loop with anintermediate portion coupled with a respective proximal element, orcoupled directly to a respective proximal element. Once the proximalelement actuator is cut by the proximal element line mandrel blade, theproximal element actuator can be withdrawn from the shaft/lumen. Asingle mandrel 404 and blade 410 can be provided to individually cuteach proximal element actuator, or a separate proximal element actuatormandrel 404 and blade 410 can be provided for each proximal elementactuator 90A and 90B for independent remove thereof.

As disclosed herein, and as shown in FIGS. 69A-B, for purpose ofillustration and not limitation, each proximal element actuator 90A and90B (wherein only proximal element actuator 90A is depicted for clarity)can include an outer sheath 90G having a window 90W formed therein, aninner mandrel 414 axially moveable relative the outer sheath 90G, and asuture extending from the outer sheath and defining a loop 412. Thesuture can be actuatable between a captured position wherein the sutureextends into the window 90W of the outer sheath 90G and receives theinner mandrel 414 through the loop 412, and a released position. Innermandrel 414 can disposed within the respective outer sheath 90G, whereininner mandrel 414 can be movable with respect to outer sheath 90B. Eachloop 412 can pass through line loop 48 of or eyelet of the respectiveproximal element 16A and 16B (wherein only proximal element 16A isdepicted for clarity), and return to the window 90W formed within outersheath 90G. Inner mandrel 414 can be passed through loop 412 within theguide sheath, fixing proximal element actuator 90A to proximal element16A. Thus, after deployment of the proximal element, proximal retractionof inner mandrel 414 can release the loop 412 and allow the proximalelement actuator 90A to be decoupled from proximal element 16A.

As further described herein, the proximal element actuators 90 can bereleasably engaged with structures that are activated by the applicationof force by the user. For example, as shown in FIG. 70, each proximalelement actuator 90A and 90B (wherein only proximal element actuator 90Ais depicted for clarity) can include a slidable outer sheath 90S and aninner member having a pincer 90P at its distal end portion, e.g.,wherein the pincer 90P includes one or more pincer prongs 90PP or thelike. The pincer 90P can be formed of shape memory material such thatthe one or more pincer prongs 90PP are biased outwardly. In this manner,the pincer prongs 90PP can be placed through the actuator loop 48 of arespective proximal element 16A and 16B (wherein only proximal element16A is depicted for clarity). Distal movement of the slidable outersheath 90S towards the pincer 90P can lock the pincer prongs 90PP in aninward position, so as to trap the line loop 48 of the proximal element16A within the pincer prongs 90PP. This can be used to secure eachproximal element actuator 90 to a respective proximal element 16 toallow independent movement and release. After deployment of the proximalelement, the slidable outer sheath 90S can be moved proximally away fromthe pincer 90P, such that the pincer prongs 90PP are no longer locked inan inward position to allow proximal element actuator 90 to decouplefrom the respective proximal element 16.

Additionally or alternatively, and referring to FIG. 71, for purpose ofillustration and not limitation, each proximal element actuator 90A and90B (wherein only proximal element actuator 90A is depicted for clarity)can be bonded directly to a respective proximal element 16A and 16B(wherein only proximal element 16A is depicted for clarity), for exampleby adhesive or welding. Each proximal element actuator 90 can include aweakened region, for example, neck-down portion 90N proximate its distalend. When the user applies a sufficient amount of proximal force to aproximal element actuator, for example, proximal element actuator 90A,proximal element actuator 90A can fracture or rupture to decouple theproximal element actuator 90A from the proximal element 16A. Forexample, a neck-down portion 90N can be dimensioned to ensure thefracture location of the proximal element actuator 90A occurs at theneck-down portion 90N. Other suitable configuration include a weakenedregion can be a scored region or other weakened in other ways.

While the methods and structures of releasably fixing the proximalelement actuators 90 are shown above with either one or two proximalelement actuators, it is possible to utilize or modify those structuresfor use with either a single or multiple proximal element actuators 90.

G. Releasably Fixing the Gripper Pushers

As set forth above, FIG. 39 highlights the gripper pusher 83 whichpreferably includes two spring arms 99. Each arm 99 is formed from wireor machined from a sheet or other stock material and in this embodimenthas a rectangular cross-section, although other cross-sections are alsocontemplated. In the embodiment of FIG. 39, a distal portion 91 of eacharm 99 has a notched region 93 forming a pair of fingers that can engagewith a boss or other attachment mechanism on the fixation device. Thenotch may be released from the boss when the fixation device 14 isdetached from the delivery catheter shaft 12. FIGS. 57 and 58 show analternative embodiment for releasably securing the arms 99 of thegripper pusher 83 in combination with an L-lock configuration.

FIGS. 57 and 58 illustrate an alternate embodiment to the mating surface32 illustrated in FIG. 6A. Here, upper shaft 500 is releasably coupledwith lower shaft 506 with a detent mechanism 504, 508. The upper andlower shafts in this embodiment are generally tubular shaped althoughone of skill in the art will appreciate that other configurations arepossible. The detent mechanism in this exemplary embodiment includes oneor more spring arms 502 integrally formed on tubular upper shaft 500 andone or more receptacles 508 sized to receive the spring arms 502.Tubular upper shaft 500 is integrally formed with one or more springarms 502 having a flange-like engagement surface 504 at a distal endthereof. The spring arms 502 are preferably biased inwardly, i.e.,toward the interior of the shaft 500. Detachable tubular lower shaft 506features one or more receptacles, here apertures 508 are configured toreceive and mate with the engagement surface 504 of the spring arm 502and an engagement surface of the arm 99 of the gripper pusher 83. Theapertures 508 may extend all the way through the wall of the lower shaft506 and are sized to snuggly fit both the engagement surface 504 of thespring arms 502 and the engagement surface 101 at the distal end 91 ofthe arms 99. To releasably couple the arms 99 to the tubular lower shaft506, the engagement surfaces 101 of the arms 99 are fitted into acorresponding aperture 508. Then, a snuggly fitting rod 34 (such asactuator rod 64) is inserted through the tubular shafts 500, 506outwardly deflecting the inwardly biased spring arm(s) 502 such that theengagement surface 504 is pushed into engagement with a correspondingreceptacle 508 and arm 99 thereby coupling the gripper pusher 83 and theupper shaft 500 to the lower shaft 506.

FIG. 58 illustrates detachment of the lower shaft 506 from the uppershaft 500. This is achieved by retracting the rod 34 to a position abovethe spring arm(s) 502 which allows the inwardly biased engagementsurface 504 to disengage from the receptacle 508 allowing the arms 99 ofthe gripper pusher 83 to separate along with the shafts 500, 506.

While the foregoing is a complete description of the preferredembodiments of the invention, various alternatives, substitutions,additions, modifications, and equivalents are possible without departingfrom the scope of the invention. For example, in many of theabove-described embodiments, the invention is described in the contextof approaching a valve structure from the upstream side—that is, theatrial side in the case of a mitral valve. It should be understood thatany of the foregoing embodiments may be utilized in other approaches aswell, including from the ventricular or downstream side of the valve, aswell as using surgical approaches through a wall of the heart. Moreover,the invention may be used in the treatment of a variety of other tissuestructures besides heart valves, and will find usefulness in a varietyof tissue approximation, attachment, closure, clamping and ligationapplications, some endovascular, some endoscopic, and some opensurgical.

Again, although the foregoing invention has been described in somedetail by way of illustration and example, for purposes of clarity ofunderstanding, it will be obvious that various alternatives,modifications and equivalents may be used and the above descriptionshould not be taken as limiting in scope of the invention which isdefined by the appended claims.

1. A fixation system for engaging tissue of a patient comprising: animplantable fixation device comprising a first arm and a second arm, afirst proximal element moveable relative to the first arm between afirst position and a second position, a second proximal element moveablerelative to the second arm between a first position and a secondposition, and a coupling member; and a delivery device comprising acatheter having a proximal end portion and a distal end portion, thecatheter defining at least one lumen extending between the proximal endportion and the distal end portion, a shaft extending through the atleast one lumen and releasably coupled to the coupling member, a firstproximal element actuator extending through the at least one lumen, thefirst proximal element actuator having a first end portion, a second endportion, and an intermediate portion between the first end portion andthe second end portion, the first proximal element actuator coupled tothe first proximal element at the intermediate portion of the firstproximal element actuator and actuatable to move the first proximalelement between the first position and the second position, and a secondproximal element actuator extending through the at least one lumen, thesecond proximal element actuator having a first end portion, a secondend portion, and an intermediate portion between the first end portionand the second end portion, the second proximal element actuator coupledto the second proximal element at the intermediate portion of the secondproximal element actuator and actuatable to move the second proximalelement between the first position and the second position; wherein thesecond end portion of the first proximal element actuator and secondproximal element actuator respectively, are coupled to at least one ofthe shaft and the coupling member.
 2. The fixation system of claim 1,wherein the first proximal element actuator and the second proximalelement actuator are released from the at least one of the shaft and thecoupling member by decoupling the shaft and coupling member.
 3. Thefixation system of claim 1, wherein the second end portion of the firstproximal element actuator comprises a first loop and the second endportion of the second proximal element actuator comprises a second loop.4. The fixation system of claim 3, wherein each of the first and secondloops is disposed around at least one of the shaft and the couplingmember when the shaft and the coupling member are coupled together. 5.The fixation system of claim 1, wherein the second end portion of thefirst proximal element actuator comprises a first catch element and thesecond end portion of the second proximal element actuator comprises asecond catch element.
 6. The fixation system of claim 5, wherein thefirst catch element comprises a first ball and the second catch elementcomprises a second ball.
 7. The fixation system of claim 5, wherein thefirst catch element comprises a first trumpet and the second catchelement comprises a second trumpet.
 8. The fixation system of claim 5,wherein the first catch element is configured to be received within afirst opening in the shaft, and the second catch element is configuredto be received within a second opening in the shaft.
 9. The fixationsystem of claim 8, wherein the first catch element and second catchelement are held in the corresponding first opening and second openingby an actuator rod received within a lumen of the shaft.
 10. Thefixation system of claim 5, wherein the first catch element and thesecond catch element are received between the shaft and the couplingmember when releasably coupled together.
 11. The fixation system ofclaim 1, wherein the delivery system further comprises a first proximalelement actuator mandrel and a second proximal element actuator mandrel,the first and second proximal element actuator mandrels extendingthrough the at least one lumen of the catheter, wherein the firstproximal element actuator mandrel is configured to releasably anchor thefirst proximal element actuator between the first proximal elementactuator mandrel and the catheter, and the second proximal elementactuator mandrel is configured to releasably anchor the second proximalelement actuator between the second proximal element actuator mandreland the catheter.
 12. The fixation system of claim 11, wherein thedelivery device further comprises a first cutter configured to cut thefirst proximal element actuator to thereby release the first proximalelement.
 13. The fixation system of claim 12, wherein the deliverydevice further comprises a second cutter configured to cut the secondproximal element actuator to thereby release the second proximalelement.
 14. A fixation system for engaging tissue of a patientcomprising: an implantable fixation device comprising a first arm and asecond arm, a first proximal element moveable relative to the first armbetween a first position and a second position, a second proximalelement moveable relative to the second arm between a first position anda second position, and a coupling member; and a delivery devicecomprising a catheter having a proximal end portion and a distal endportion, the catheter defining at least one lumen extending between theproximal end portion and the distal end portion, a shaft extendingthrough the at least one lumen and releasably coupled to the couplingmember, a first proximal element actuator extending through the at leastone lumen, the first proximal element actuator having a first endportion and a second end portion, the first proximal element actuatorcoupled to the first proximal element at the second end portion of thefirst proximal element actuator and actuatable to move the firstproximal element between the first position and the second position, anda second proximal element actuator extending through the at least onelumen, the second proximal element actuator having a first end portionand a second end portion, the second proximal element actuator coupledto the second proximal element at the second end portion of the secondproximal element actuator and actuatable to move the second proximalelement between the first position and the second position.
 15. Thefixation system of claim 14, the first proximal element actuator and thesecond proximal element actuator each comprises an outer sheath having afirst window, an inner mandrel axially moveable relative the outersheath, and a suture extending from the outer sheath and defining aloop, wherein the suture is actuatable between a captured positionwherein the suture extends into the window of the outer sheath andreceives the inner mandrel through the loop, and a released position.16. The fixation system of claim 14, wherein the first proximal elementactuator and the second proximal element actuator each comprises anouter sheath axially moveable relative an inner member having a distalpincer, wherein the outer sheath is configured to close the pincer bymoving distally relative the inner member and to open the pincer bymoving proximally relative the inner member.
 17. The fixation system ofclaim 14, wherein the first proximal element actuator and the secondproximal element actuator each comprises a weakened region proximal thesecond end portion.
 18. A fixation system for engaging tissue of apatient comprising: an implantable fixation device comprising a firstarm and a second arm, a first proximal element moveable relative to thefirst arm between a first position and a second position, a secondproximal element moveable relative to the second arm between a firstposition and a second position, and a coupling member; and a deliverydevice comprising a catheter having a proximal end portion and a distalend portion, the catheter defining at least one lumen extending betweenthe proximal end portion and the distal end portion, a shaft extendingthrough the at least one lumen and releasably coupled to the couplingmember, a first proximal element actuator extending distally through theat least one lumen and back proximally through the at least one lumen todefine a loop extending from the distal end portion of the catheter, theloop of the first proximal element actuator coupled to the firstproximal element and actuatable to move the first proximal elementbetween the first position and second position, and a second proximalelement actuator extending distally through the at least one lumen andback proximally through the at least one lumen to define a loopextending from the distal end portion of the catheter, the loop of thesecond proximal element actuator coupled to the second proximal elementand actuatable to move the second proximal element between the firstposition and second position; wherein the loop defined by the firstproximal element actuator and the loop defined by the second proximalelement actuator are each coupled to at least one of the shaft and thecoupling member.